SSM编写http接口返回JSON格式数据

悠悠 2022-06-05 06:00 313阅读 0赞

由于前后端数据分离的强烈需要,现在越来越需要接口化的开发,特别是服务器端的开发和移动端后台的开发,前后端的数据交互自然不能使用之前直接传数据的方式,于是JSON便成了最佳的选择,JSON的底层是HashMap,键值对的方式可以生成或解析JavaBean,既能满足要求,又不失开发效率.下面开发一个简单的获取某个id数据的接口,给访问的前端返回JSON数据.

代码:

**一.获取数据库中的数据**

\#数据模型层

package com.east.entity;
    
    import java.io.Serializable;
    import java.sql.Timestamp;
    
    public class Inform implements Serializable {
    	private Integer info_id;
    	private String  info_title;
    	private String  info_content;
    	private Timestamp info_time;
    	public Integer getInfo_id() {
    		return info_id;
    	}
    	public void setInfo_id(Integer info_id) {
    		this.info_id = info_id;
    	}
    	public String getInfo_title() {
    		return info_title;
    	}
    	public void setInfo_title(String info_title) {
    		this.info_title = info_title;
    	}
    	public String getInfo_content() {
    		return info_content;
    	}
    	public void setInfo_content(String info_content) {
    		this.info_content = info_content;
    	}
    	public Timestamp getInfo_time() {
    		return info_time;
    	}
    	public void setInfo_time(Timestamp info_time) {
    		this.info_time = info_time;
    	}
    	@Override
    	public String toString() {
    		return "Inform [info_id=" + info_id + ", info_title=" + info_title + ", info_content=" + info_content
    				+ ", info_time=" + info_time + "]";
    	}
    	
    }

\#数据访问层

package com.east.dao;
    
    import java.util.List;
    
    import org.apache.ibatis.annotations.Delete;
    import org.apache.ibatis.annotations.Insert;
    import org.apache.ibatis.annotations.Options;
    import org.apache.ibatis.annotations.Param;
    import org.apache.ibatis.annotations.Select;
    
    import com.east.entity.Inform;
    
    public interface InformDao {
    	
    	/*
    	 * 查询某个公告的信息
    	 */
    	@Select("select * from inform where info_id = #{info_id}")
    	Inform findById(Integer info_id);
    }

\#业务逻辑层

package com.east.biz;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Service;
    import org.springframework.transaction.annotation.Isolation;
    import org.springframework.transaction.annotation.Propagation;
    import org.springframework.transaction.annotation.Transactional;
    
    import com.east.dao.InformDao;
    import com.east.entity.Inform;
    
    @Transactional(propagation=Propagation.REQUIRED,isolation=Isolation.DEFAULT)
    @Service("informBiz")
    public class InformBiz {
        /*
         * 自动注入InformDao
         */
    	@Autowired
    	private InformDao informDao;
    	
    	public Inform findById(Integer info_id){
    		return informDao.findById(info_id);
    	}
    }

**二.JSON操作相关的对象类**

package com.east.util;
    
    import java.util.Date;
    
    /*
     * 建立AbstractJSON(JSON数据的响应基类 )
     */
    public class AbstractJSON {
    	private String code;                            //响应状态码 
    	private String msg;                             //响应状态描述  
    	private Long time = new Date().getTime();       //时间戳  
    
    	public String getCode() {
    		return code;
    	}
    
    	public void setCode(String code) {
    		this.code = code;
    	}
    
    	public String getMsg() {
    		return msg;
    	}
    
    	public void setMsg(String msg) {
    		this.msg = msg;
    	}
    
    	public Long getTime() {
    		return time;
    	}
    
    	public void setTime(Long time) {
    		this.time = time;
    	}
    
    	public void setContent(String code, String msg) {
    		this.code = code;
    		this.msg = msg;
    	}
    
    	public void setStatusObject(StatusObject statusObject) {
    		this.code = statusObject.getCode();
    		this.msg = statusObject.getMsg();
    	}
    }

package com.east.util;
    
    import java.io.FileReader;
    import java.io.FileWriter;
    import java.io.IOException;
    import java.io.StringWriter;
    
    import com.fasterxml.jackson.core.JsonFactory;
    import com.fasterxml.jackson.core.JsonGenerator;
    import com.fasterxml.jackson.core.JsonParseException;
    import com.fasterxml.jackson.databind.JsonMappingException;
    import com.fasterxml.jackson.databind.ObjectMapper;
    
    public class JsonWriter {
    	private static ObjectMapper om = new ObjectMapper();
    	private static JsonFactory jf = new JsonFactory();
    
    	public static <T> Object fromJson(String jsonAsString, Class<T> pojoClass) {
    		try {
    			return om.readValue(jsonAsString, pojoClass);
    		} catch (JsonParseException e) {
    			throw new IllegalStateException(e.getMessage(), e);
    		} catch (JsonMappingException e) {
    			throw new IllegalStateException(e.getMessage(), e);
    		} catch (IOException e) {
    			throw new IllegalStateException(e.getMessage(), e);
    		}
    	}
    
    	public static <T> Object fromJson(FileReader fr, Class<T> pojoClass) {
    		try {
    			return om.readValue(fr, pojoClass);
    		} catch (JsonParseException e) {
    			throw new IllegalStateException(e.getMessage(), e);
    		} catch (JsonMappingException e) {
    			throw new IllegalStateException(e.getMessage(), e);
    		} catch (IOException e) {
    			throw new IllegalStateException(e.getMessage(), e);
    		}
    	}
    
    	public static String toJson(Object pojo, boolean prettyPrint) {
    		try {
    			StringWriter sw = new StringWriter();
    			JsonGenerator jg = jf.createGenerator(sw);
    
    			if (prettyPrint) {
    				jg.useDefaultPrettyPrinter();
    			}
    			om.writeValue(jg, pojo);
    			return sw.toString();
    		} catch (JsonParseException e) {
    			throw new IllegalStateException(e.getMessage(), e);
    		} catch (JsonMappingException e) {
    			throw new IllegalStateException(e.getMessage(), e);
    		} catch (IOException e) {
    			throw new IllegalStateException(e.getMessage(), e);
    		}
    	}
    
    	public static void toJson(Object pojo, FileWriter fw, boolean prettyPrint) {
    		try {
    			JsonGenerator jg = jf.createGenerator(fw);
    			if (prettyPrint) {
    				jg.useDefaultPrettyPrinter();
    			}
    			om.writeValue(jg, pojo);
    		} catch (JsonParseException e) {
    			throw new IllegalStateException(e.getMessage(), e);
    		} catch (JsonMappingException e) {
    			throw new IllegalStateException(e.getMessage(), e);
    		} catch (IOException e) {
    			throw new IllegalStateException(e.getMessage(), e);
    		}
    	}
    
    	public static String toJson(Object pojo) {
    		return toJson(pojo, false);
    	}
    
    }

package com.east.util;
    
    import java.util.List;
    
    /*
     * 建立JSON数组类ListObject
     */
    public class ListObject extends AbstractJSON {
    
        private List<?> items;                       // 列表对象
    
    	public List<?> getItems() {
    		return items;
    	}
    
    	public void setItems(List<?> items) {
    		this.items = items;
    	}
        
    }

package com.east.util;
    
    import com.fasterxml.jackson.databind.ObjectMapper;
    
    /*
     * JsonUtils生成json数据和解析json数据
     */
    public class JsonUtils {
    	static ObjectMapper objectMapper;
    
    	/*
    	 * 解析json
    	 */
    	public static <T> T fromJson(String content, Class<T> valueType) {
    		if (objectMapper == null) {
    			objectMapper = new ObjectMapper();
    		}
    		try {
    			return objectMapper.readValue(content, valueType);
    		} catch (Exception e) {
    			e.printStackTrace();
    		}
    		return null;
    	}
    
    	/*
    	 * 生成json
    	 */
    	public static String toJson(Object object) {
    		if (objectMapper == null) {
    			objectMapper = new ObjectMapper();
    		}
    		try {
    			return objectMapper.writeValueAsString(object);
    		} catch (Exception e) {
    			e.printStackTrace();
    		}
    		return null;
    	}
    }

package com.east.util;
    
    /*
     * 建立JSON对象类SingleObject
     */
    public class SingleObject extends AbstractJSON {
    	private Object object;
    
    	public Object getObject() {
    		return object;
    	}
    
    	public void setObject(Object object) {
    		this.object = object;
    	} 
    	
    }

package com.east.util;
    
    /*
     * 定义状态码
     */
    public class StatusCode {
    
    	public static String CODE_SUCCESS = "ok";          //访问成功 
    
    	public static String CODE_ERROR = "0001";          //访问错误 
    
    	public static String CODE_ERROR_PARAMETER = "0002";//参数错误
    
    	public static String CODE_ERROR_PROGRAM = "0003";  //程序异常
    
    	public static String CODE_ERROR_NO_LOGIN_OR_TIMEOUT = "0004";  //未登录或登录超时,请重新登录 
    
    	public static String CODE_ERROR_EXIST_OPERATION = "0005";      //已操作
    
    }

package com.east.util;
    
    import java.io.IOException;
    
    import javax.servlet.http.HttpServletResponse;
    
    /*
     * 响应处理
     */
    public class ResponseUtils {
    
    	/*
    	 * 返回json串
    	 */
    	public static void renderJson(HttpServletResponse response, String text) {
    		// System.out.print(text);
    		render(response, "text/plain;charset=UTF-8", text);
    	}
    
    	/*
    	 * 返回文本
    	 */
    	public static void renderText(HttpServletResponse response, String text) {
    		render(response, "text/plain;charset=UTF-8", text);
    	}
    
    	/*
    	 * 发送内容,使用UTF-8编码
    	 */
    	public static void render(HttpServletResponse response, String contentType, String text) {
    		response.setContentType(contentType);
    		response.setCharacterEncoding("utf-8");
    		response.setHeader("Pragma", "No-cache");
    		response.setHeader("Cache-Control", "no-cache");
    		response.setDateHeader("Expires", 0);
    		try {
    			response.getWriter().write(text);
    		} catch (IOException e) {
    		}
    	}
    	
    	/*
    	 * 页面异步回调返回Json
    	 */
    	public static void outputJson(HttpServletResponse response, Object obj) {
    		String s = JsonWriter.toJson(obj, false);
    		response.setContentType("text/plain;charset=UTF-8");
    		response.setHeader("Pragma", "No-cache");
    		response.setHeader("Cache-Control", "no-cache");
    		response.setDateHeader("Expires", 0);
    		try {
    			response.getWriter().write(s);
    		} catch (IOException e) {
    			e.printStackTrace();
    		}
    	}
    }

**三.控制层(前端请求的路径)**

package com.east.action;
    
    import java.util.ArrayList;
    import java.util.List;
    
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.beans.factory.annotation.Qualifier;
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.RequestMapping;
    
    import com.east.biz.InformBiz;
    import com.east.entity.Inform;
    import com.east.util.JsonUtils;
    import com.east.util.ListObject;
    import com.east.util.ResponseUtils;
    import com.east.util.StatusCode;
    
    /*
     * 处理用户请求的控制器
     */
    @Controller
    public class InformAction {
    	// 自动注入UserService
    	@Autowired
    	@Qualifier("informBiz")
    	private InformBiz informBiz;
    
    	/*
    	 * 获取指定id的公告
    	 */
    	@RequestMapping(value = "/findById")
    	public void findById(String info_id, HttpServletRequest request, HttpServletResponse response) {
    		Integer id = Integer.parseInt(info_id);
    		Inform inform = informBiz.findById(id);
    		List<Inform> list = new ArrayList<Inform>();
    		list.add(inform);
    		ListObject listObject = new ListObject();
    		listObject.setItems(list);
    		listObject.setCode(StatusCode.CODE_SUCCESS);
    		listObject.setMsg("访问成功");
    		ResponseUtils.renderJson(response, JsonUtils.toJson(listObject));
    	}
    }

**四.到此,接口开发圆满完成,看看效果**

接口的链接为:http://localhost:8098/InterfaceTest/findById?info\_id=1

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[Center]: /images/20220605/130a73f0074c46e89985416a42918256.png