android与java web交互完成简单的登录和注册

港控/mmm° 2022-05-27 10:14 173阅读 0赞

**本文的知识点包括android客户端的网络编程、消息机制、IO流、多线程和java web服务器端的servlet、数据库操作、javabean技术、工具类和测试类的使用。**

**客户端**

运行效果图

![20180416232233955][]![20180416232249225][]![20180416232305756][]![2018041623231871][]

布局文件

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        tools:context="com.ningxiaojian.clientlogindemo.MainActivity">
    
        <EditText
            android:id="@+id/et_username"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="请输入登录账号"/>
    
        <EditText
            android:id="@+id/et_password"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="请输入登录密码"/>
    
        <Button
            android:id="@+id/bt_login"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="登录"
            android:onClick="login"/>
    
        <Button
            android:id="@+id/bt_register"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="注册"
            android:onClick="register"/>
    
    
    </LinearLayout>

程序主入口
    MainActivity

package com.ningxiaojian.clientlogindemo;
    
    import android.annotation.SuppressLint;
    import android.os.Handler;
    import android.os.Message;
    import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;
    import android.view.View;
    import android.widget.EditText;
    import android.widget.Toast;
    
    import java.io.InputStream;
    import java.io.OutputStream;
    import java.io.UnsupportedEncodingException;
    import java.net.HttpURLConnection;
    import java.net.MalformedURLException;
    import java.net.URL;
    import java.net.URLConnection;
    import java.net.URLEncoder;
    
    public class MainActivity extends AppCompatActivity {
    
        private EditText username;
        private EditText password;
        private String usernameStr;
        private String passwordStr;
        private final int LOGINSUCCESS=0;
        private final int LOGINNOTFOUND=1;
        private final int LOGINEXCEPT=2;
        private final int REGISTERSUCCESS=3;
        private final int REGISTERNOTFOUND=4;
        private final int REGISTEREXCEPT=5;
    
        @SuppressLint("HandlerLeak")
        Handler handler=new Handler(){//消息机制，用来在子线程中更新UI
            @Override
            public void handleMessage(Message msg) {
                switch (msg.what){//具体消息，具体显示
                    case LOGINSUCCESS:
                        Toast.makeText(getApplicationContext(),(String)msg.obj,Toast.LENGTH_LONG).show();
                        break;
                    case LOGINNOTFOUND:
                        Toast.makeText(getApplicationContext(),(String)msg.obj,Toast.LENGTH_LONG).show();
                        break;
                    case LOGINEXCEPT:
                        Toast.makeText(getApplicationContext(),(String)msg.obj,Toast.LENGTH_LONG).show();
                        break;
                    case REGISTERSUCCESS:
                        Toast.makeText(getApplicationContext(),(String)msg.obj,Toast.LENGTH_LONG).show();
                        break;
                    case REGISTERNOTFOUND:
                        Toast.makeText(getApplicationContext(),(String)msg.obj,Toast.LENGTH_LONG).show();
                        break;
                    case REGISTEREXCEPT:
                        Toast.makeText(getApplicationContext(),(String)msg.obj,Toast.LENGTH_LONG).show();
                        break;
                }
            }
        };
    
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            //找到我们需要的控件
            username = (EditText) findViewById(R.id.et_username);
            password = (EditText) findViewById(R.id.et_password);
    
    
        }
        //登录按钮的点击事件，也可以用set监听器的方法，不过这种方法简单
        public void login(View v){
            //获取编辑框内的内容
            usernameStr = username.getText().toString().trim();
            passwordStr = password.getText().toString().trim();
    
            //判断是否输入为空（在这里就不再进行正则表达式判断了）
            if(usernameStr.equals("") || passwordStr.equals("")){
                Toast.makeText(MainActivity.this,"用户名或密码不能为空",Toast.LENGTH_SHORT).show();
            }//进行登录操作(联网操作要添加权限)
            else {
                //联网操作要开子线程，在主线程不能更新UI
                new Thread(){
    
                    private HttpURLConnection connection;
    
    
                    @Override
                    public void run() {
    
                        try {
                            //封装成传输数据的键值对,无论get还是post,传输中文时都要进行url编码（RULEncoder）
                            // 如果是在浏览器端的话，它会自动进行帮我们转码，不用我们进行手动设置
                            String data2= "username="+ URLEncoder.encode(usernameStr,"utf-8")+"&password="+ URLEncoder.encode(passwordStr,"utf-8")+"&sign="+URLEncoder.encode("1","utf-8");
                            connection=HttpConnectionUtils.getConnection(data2);
                            int code = connection.getResponseCode();
                            if(code==200){
                                InputStream inputStream = connection.getInputStream();
                                String str = StreamChangeStrUtils.toChange(inputStream);//写个工具类流转换成字符串
                                Message message = Message.obtain();//更新UI就要向消息机制发送消息
                                message.what=LOGINSUCCESS;//用来标志是哪个消息
                                message.obj=str;//消息主体
                                handler.sendMessage(message);
    
                            }
                            else {
                                Message message = Message.obtain();
                                message.what=LOGINNOTFOUND;
                                message.obj="注册异常...请稍后再试";
                                handler.sendMessage(message);
                            }
                        } catch (Exception e) {//会抛出很多个异常，这里抓一个大的异常
                            e.printStackTrace();
                            Message message = Message.obtain();
                            message.what=LOGINEXCEPT;
                            message.obj="服务器异常...请稍后再试";
                            handler.sendMessage(message);
                        }
                    }
                }.start();//不要忘记开线程
            }
        }
        //注册按钮的点击事件
        public void register(View v){
            usernameStr = username.getText().toString().trim();
            passwordStr = password.getText().toString().trim();
            if(usernameStr.equals("") || passwordStr.equals("")){
                Toast.makeText(MainActivity.this,"用户名或密码不能为空",Toast.LENGTH_SHORT).show();
            }
            else {
                    new Thread(){
    
                        HttpURLConnection connection=null;
                        @Override
                        public void run() {
                            try {
                                String data= "username="+ URLEncoder.encode(usernameStr,"utf-8")+"&password="+ URLEncoder.encode(passwordStr,"utf-8")+"&sign="+URLEncoder.encode("2","utf-8");
                                connection=HttpConnectionUtils.getConnection(data);
                                int code = connection.getResponseCode();
                                if(code==200){
                                    InputStream inputStream = connection.getInputStream();
                                    String str = StreamChangeStrUtils.toChange(inputStream);
                                    Message message = Message.obtain();
                                    message.obj=str;
                                    message.what=REGISTERSUCCESS;
                                    handler.sendMessage(message);
                                }
                                else {
                                    Message message = Message.obtain();
                                    message.what=REGISTERNOTFOUND;
                                    message.obj="注册异常...请稍后再试";
                                    handler.sendMessage(message);
                                }
                            } catch (Exception e) {
                                e.printStackTrace();
                                Message message = Message.obtain();
                                message.what=REGISTEREXCEPT;
                                message.obj="服务器异常...请稍后再试";
                                handler.sendMessage(message);
                            }
    
                        }
                    }.start();//不要忘记开线程
    
            }
        }
    }

流转换成字符串的工具类
    StreamChangeStrUtils

package com.ningxiaojian.clientlogindemo;
    
    import java.io.ByteArrayOutputStream;
    import java.io.IOException;
    import java.io.InputStream;
    
    /**
     * 流转换成字符串的工具类
     */
    
    public class StreamChangeStrUtils {
        public static String toChange(InputStream inputStream) throws Exception {
            ByteArrayOutputStream bos = new ByteArrayOutputStream();//数组流，在流的内部有个缓冲区，可以进行转换成字节
            //下面是属于io流的知识，在此不再赘述
            byte b[]=new byte[1024];
            int len=-1;
            while ((len=inputStream.read(b))!=-1){
                bos.write(b,0,len);
            }
            inputStream.close();//关闭流,数组流会自动关闭，关闭是否都可以
            String str = new String(bos.toByteArray());
            //服务器默认返回的是gbk，如果要在android端解决乱码，可以在此设置为gbk,一般提倡的是服务器解决
            // 让服务器给我们返回utf-8，因为在android本地默认的是utf-8
            return str;
        }
    }

联网工具类

HttpConnectionUtils

package com.ningxiaojian.clientlogindemo;
    
    import android.os.Message;
    
    import java.io.InputStream;
    import java.io.OutputStream;
    import java.net.HttpURLConnection;
    import java.net.ProtocolException;
    import java.net.URL;
    import java.net.URLEncoder;
    
    /**
     * 获取联网连接
     * Created by Justin on 2018/4/16.
     */
    
    public class HttpConnectionUtils {
        public static HttpURLConnection getConnection(String data) throws Exception {
    
                //通过URL对象获取联网对象
                URL url= new URL("http://192.168.1.104:8080/AndroidLoginDemo/LoginServlet");
                HttpURLConnection connection = (HttpURLConnection) url.openConnection();
                connection.setRequestMethod("POST");//设置post请求
                connection.setReadTimeout(5000);//设置5s的响应时间
                connection.setDoOutput(true);//允许输出
                connection.setDoInput(true);//允许输入
                //设置请求头，以键值对的方式传输（以下这两点在GET请求中不用设置）
                connection.setRequestProperty("Content-Type","application/x-www-form-urlencoded ");
                connection.setRequestProperty("Content-Length",data.length()+"");//设置请求体的长度
                OutputStream outputStream = connection.getOutputStream();
                outputStream.write(data.getBytes());//进行传输操作
                //判断服务端返回的响应码，这里是http协议的内容
                return connection;
        }
    }

联网操作一定要在

AndroidManifest.xml加上权限

<uses-permission android:name="android.permission.INTERNET"/>
    
    服务器端（Tomcat）
    
    首先去mysql创建一个数据库，表结构如下
    因为使用到mysql,所以要把jdbc的驱动类添加到webcontent->web-inf->lib中
    mysql-connector-java-5.1.45-bin.jar
    
    在eclipse创建以下包名
    
    com.ningxiaojian.dao:dao层接口
    com.ningxiaojian.dao.impl:dao层接口的实现
    com.ningxiaojian.domain：javabean对象
    com.ningxiaojian.service：逻辑层的接口
    com.ningxiaojian.service.impl:逻辑层的实现
    com.ningxiaojian.web.control：存放servlet
    com.ningxiaojian.utils:存放工具类
    com.ninxiaojian.test：存放测试类
    
    创建java对象
    User.java

package com.ningxiaojian.domain;
    
    /**
     *
     *设置一个javabean对象，用来封装dao层取出的数据
     * @author Justin
     *
     */
    public class User {
    	private String username;
    	private String password;
    	public String getUsername() {
    		return username;
    	}
    	public void setUsername(String username) {
    		this.username = username;
    	}
    	public String getPassword() {
    		return password;
    	}
    	public void setPassword(String password) {
    		this.password = password;
    	}
    	
    }

dao层接口  
UserDao.java

package com.ningxiaojian.dao;
    
    import java.util.List;
    
    import com.ningxiaojian.domain.User;
    
    public interface UserDao {
    	//找到所有元素,用来验证登录信息
    	public  List<User> findAll();
    	//插入元素,用来注册
    	public void insertElement(User people);
    	
    }

dao层实现类  
UserDaoImpl.java

package com.ningxiaojian.dao.impl;
    
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    import java.util.ArrayList;
    import java.util.List;
    
    import com.ningxiaojian.dao.UserDao;
    import com.ningxiaojian.domain.User;
    import com.ningxiaojian.utils.JDBCUtils;
    
    public class UserDaoImpl implements UserDao {
    
    	Connection connection=null;
    	PreparedStatement ps=null;
    	ResultSet rs=null;
    	
    	/**
    	 * dao层，从数据库里面取出数据
    	 */
    	@Override
    	public List<User> findAll() {
    		List<User> list=null;
    		try {
    			//通过工具类获得连接
    			connection = JDBCUtils.getConnetion();
    			//通过连接对象获取操作数据库的对象
    			String sql="SELECT * FROM user;";//查询sql语句
    			ps=connection.prepareStatement(sql);
    			//返回查询结果集
    			rs=ps.executeQuery();
    			//遍历rs，并封装数据
    			list=new ArrayList<User>();
    			while(rs.next()) {
    				User user=new User();
    				user.setUsername(rs.getString(2));//索引从1开始，id参数不用取
    				user.setPassword(rs.getString(3));
    				list.add(user);
    			}
    			
    		} catch (Exception e) {
    			e.printStackTrace();
    		}
    		finally{
    			JDBCUtils.close(connection, ps, rs);//关闭连接
    			
    		}
    		return list;
    	}
    
    	@Override
    	public void insertElement(User people) {
    		try {
    			connection=JDBCUtils.getConnetion();
    			String sql="INSERT INTO user(username,password) VALUES(?,?);";//插入语句
    			ps=connection.prepareStatement(sql);
    			ps.setString(1,people.getUsername());//使用prepareStatement可以防止sql注入
    			ps.setString(2,people.getPassword());
    			//执行更新语句
    			ps.executeUpdate();
    		} catch (Exception e) {
    			e.printStackTrace();
    		}
    		finally {
    			JDBCUtils.close(connection, ps, rs);
    		}
    	}
    
    }

jdbc工具类  
JDBCUtils.java

package com.ningxiaojian.utils;
    
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    
    
    
    /**
     * 因为要多次用到以下的步骤，所以写一个工具类来操作jdbc
     * @author Justin
     *在这里不要导错包，import com.mysql.jdbc.PreparedStatement;是错的
     */
    public class JDBCUtils {
    	/**
    	 * 获得jdbc连接
    	 */
    	static Connection connection=null;
    	public static Connection getConnetion() throws Exception {
    		//加载jdbc驱动
    		Class.forName("com.mysql.jdbc.Driver");
    		//创建连接数据库的路径
    		String url = "jdbc:mysql://localhost/android_login?user=root&password=12345";
    		//通过url获得与数据库的连接
    		connection = DriverManager.getConnection(url);
    		return connection;
    	}
    	
    	public static void close(Connection connection,PreparedStatement ps,ResultSet rs) {
    		//一定要确保关闭连接，以下关闭步骤是参照官方文档的，有权威性
    		if(rs!=null) {
    			try {
    				rs.close();
    			} catch (SQLException e) {
    				e.printStackTrace();
    			}
    		}
    		if(ps!=null) {
    			try {
    				ps.close();
    			} catch (SQLException e) {
    				e.printStackTrace();
    			}
    		}
    		if(connection!=null) {
    			try {
    				connection.close();
    			} catch (SQLException e) {
    				e.printStackTrace();
    			}
    		}
    	}
    }

测试dao层方法的test类（仅作测试作用）  
TestDao.java

package com.ninxiaojian.test;
    
    import java.util.List;
    
    import org.junit.jupiter.api.Test;
    
    import com.ningxiaojian.dao.UserDao;
    import com.ningxiaojian.dao.impl.UserDaoImpl;
    import com.ningxiaojian.domain.User;
    
    class TestDao {
    
    	/**
    	 * 测试类，测试dao层那两个方法是否查询和插入正确
    	 */
    	@Test
    	void testFindAll() {
    		UserDao dao=new UserDaoImpl();
    		List<User> list = dao.findAll();
    		for(int i=0;i<list.size();i++) {//遍历list
    			User user=list.get(i);
    			System.out.println("username:"+user.getUsername());
    			System.out.println("password:"+user.getPassword());
    		}
    	}
    	@Test
    	void testInsertElement() {
    		UserDao dao=new UserDaoImpl();
    		User people=new User();
    		people.setUsername("hhhhh");
    		people.setPassword("66666");
    		dao.insertElement(people);
    	}
    
    }

servlet类  
LoginServlet.java

package com.ningxiaojian.web.control;
    
    import java.io.IOException;
    import java.io.PrintWriter;
    
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    import com.ningxiaojian.domain.User;
    import com.ningxiaojian.service.UserService;
    import com.ningxiaojian.service.impl.UserServiceImpl;
    
    
    @WebServlet("/LoginServlet")
    public class LoginServlet extends HttpServlet {
    	private static final long serialVersionUID = 1L;
       
    	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    		request.setCharacterEncoding("UTF-8");//解决请求乱码(post)
    		response.setCharacterEncoding("UTF-8");//解决响应乱码,下面要以字符流输出（若字节流输出则要再次编码）
    		String username=request.getParameter("username");
    		String password=request.getParameter("password");
    		String sign=request.getParameter("sign");
    		PrintWriter out=response.getWriter();
    		//把传来的数据封装进javabean中
    		User user=new User();
    		user.setUsername(username);
    		user.setPassword(password);
    		UserService service=new UserServiceImpl();
    		if("1".equals(sign)) {//登录操作(设置了一个标记)
    			String loginInfo=service.checkLogin(user);
    			out.print(loginInfo);
    		}
    		else if("2".equals(sign)) {//注册操作
    			String registerInfo=service.register(user);
    			out.print(registerInfo);
    		}
    		
    		System.out.println(username);//在控制台输出
    		System.out.println(password);
    		System.out.println(sign);
    		
    	
    	}
    
    	
    	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    		doGet(request, response);
    	}
    
    }

service接口层  
UserService.java

package com.ningxiaojian.service;
    
    import com.ningxiaojian.domain.User;
    
    public interface UserService {
    	//查验登录
    	public String checkLogin(User user);
    	//注册用户
    	public String register(User user);
    }

service实现层，服务端的主要逻辑  
UserServiceImpl.java

package com.ningxiaojian.service.impl;
    
    import java.util.List;
    
    import com.ningxiaojian.dao.UserDao;
    import com.ningxiaojian.dao.impl.UserDaoImpl;
    import com.ningxiaojian.domain.User;
    import com.ningxiaojian.service.UserService;
    
    public class UserServiceImpl implements UserService {
    
    	UserDao dao=new UserDaoImpl();
    	
    	/*
    	 * 主要的逻辑实现
    	 */
    	@Override
    	public String checkLogin(User user) {
    		List<User> list = dao.findAll();
    		for(int i=0;i<list.size();i++) {//遍历集合
    			User user2=list.get(i);
    			if(user2.getUsername().equals(user.getUsername()) && user2.getPassword().equals(user.getPassword())) {
    				return "登录成功";
    			}
    		}
    		return "登录失败,密码输入错误";
    	}
    
    	@Override
    	public String register(User user) {
    		List<User> list = dao.findAll();
    		for(int i=0;i<list.size();i++) {
    			User user2=list.get(i);
    			if(user2.getUsername().equals(user.getUsername())) {
    				return "注册失败，该用户名已存在！";
    			}
    		}
    		dao.insertElement(user);
    		return "注册成功";
    	}
    
    }

以上就是全部的代码，每句代码都会有详细的解释

[20180416232233955]: https://img-blog.csdn.net/20180416232233955
[20180416232249225]: https://img-blog.csdn.net/20180416232249225
[20180416232305756]: https://img-blog.csdn.net/20180416232305756
[2018041623231871]: /images/20220527/4f877f9d05554f1dba7750f418579a3d.png