Intent实现页面跳转和传值

古城微笑少年丶 2022-04-17 05:55 336阅读 0赞

\*Intent称为意图，是Android各大组件连接的桥梁

**1.Activity页面跳转**

*同一个包内*

Intent intent = new Intent();
    intent.setClass(MainActivity.this, SecondActivity.class);  
    MainActivity.this.startActivity(intent);

*不同包内*

*(1)明确的Intent*

Intent intent = new Intent();
    ComponentName comp = new ComponentName("包名(应用本身所在的包，通过AndroidManifest.xml中package属性查看)","包名.类名(Activity所在的包)");
    //或者intent.setClassName("包名","包名.类名");
    intent.setComponent(comp);
    startActivity(intent);

(2)不明确的Intent

Intent intent = new Intent();
    intent.setAction(Intent.ACTION_MAIN); // 应用程序的入口
    intent.addCategory(Intent.CATEGORY_HOME); // 桌面的应用程序
    startActivity(intent);

然后在AndroidManifest.xml中注册该过滤条件

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注：

\*第一个Activity是外部通过不明确的Intent跳转的

\*要设置第一个被启动的Activity，需要设置如下属性

<intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>

**2.Activity页面跳转传值**

*第一种方法：(Intent)*

发送方：

Intent intent = new Intent();
    intent.putExtra("name", "诸葛亮");
    intent.putExtra("age", 50);
    intent.putExtra("IQ", 200.0f);
    intent.setClass(MainActivity.this, SecondActivity.class);
    MainActivity.this.startActivity(intent);

接受方：

Intent intent = getIntent();
    String name = intent.getStringExtra("name");
    int age = intent.getIntExtra("age", 0);
    float IQ = intent.getFloatExtra("IQ", 0.0f);
    textview2.setText("name:"+name+",age:"+age+",IQ:"+IQ);

*第二种方法：(Bundle)*

发送方：

![复制代码][copycode.gif]

Intent intent = new Intent();
    Bundle bundle = new Bundle();
    bundle.putString("name", "乔峰");
    bundle.putInt("age", 40);
    bundle.putFloat("weight", 70.4f);
    intent.putExtras(bundle);
    intent.setClass(MainActivity.this, SecondActivity.class);
    startActivity(intent);

![复制代码][copycode.gif]

接受方:

Intent intent = getIntent();
    Bundle bundle = intent.getExtras();
    String name = bundle.getString("name");
    int age = bundle.getInt("age");
    float weight = bundle.getFloat("weight");
    textview.setText(name+","+age+","+weight);

*第三种方法：(Application)*

首先要新建一个继承Application的MyApp类，补充属性的get/set方法

AndroidManifest.xml也要配置application的属性android:name=".MyApp"

发送方：

MyApp myApp = (MyApp) getApplication();
    myApp.setName("周星驰");
    Intent intent = new Intent();
    intent.setClass(MainActivity.this, SecondActivity.class);
    startActivity(intent);

接受方：

MyApp myApp = (MyApp) getApplication();
    String name = myApp.getName();
    textview = (TextView) findViewById(R.id.textview);
    textview.setText(name);

***第四种方法：(推荐)***

**对象类要实现Parclelable接口**

发送方：

Intent intent = new Intent();
    Person person = new Person("孙悟空",500,55.6f);
    intent.putExtra("person", person);
    intent.setClass(MainActivity.this, SecondActivity.class);
    startActivity(intent);

接受方：

Intent intent = getIntent();
    Person person = intent.getParcelableExtra("person");
    textview = (TextView) findViewById(R.id.textview);
    textview.setText(person.toString());

对象类：

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public class Person implements Parcelable {
        private String name;
        private int age;
        private float weight;
    
        public Person() {
            super();
            // TODO Auto-generated constructor stub
        }
    
        public Person(String name, int age, float weight) {
            super();
            this.name = name;
            this.age = age;
            this.weight = weight;
        }
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public int getAge() {
            return age;
        }
    
        public void setAge(int age) {
            this.age = age;
        }
    
        public float getWeight() {
            return weight;
        }
    
        public void setWeight(float weight) {
            this.weight = weight;
        }
    
        @Override
        public String toString() {
            return "Person [name=" + name + ", age=" + age + ", weight=" + weight + "]";
        }
    
        @Override
        public int describeContents() {
            return 0;
        }
    
        @Override
        public void writeToParcel(Parcel dest, int flags) {
            dest.writeString(name);
            dest.writeInt(age);
            dest.writeFloat(weight);
        }
    
        public static final Parcelable.Creator<Person> CREATOR = new Parcelable.Creator<Person>() {
            public Person createFromParcel(Parcel in) {
                return new Person(in);
            }
    
            public Person[] newArray(int size) {
                return new Person[size];
            }
        };
    
        private Person(Parcel in) {
            name = in.readString();
            age = in.readInt();
            weight = in.readFloat();
        }
    }

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**3.页面返回传值**

被返回方：

startActivityForResult(intent, 38);

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@Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        Bundle bundle = data.getExtras();
        String name = bundle.getString("name");
        int age = bundle.getInt("age");
        float weight = bundle.getFloat("weight");
        Toast.makeText(MainActivity.this, name+age+weight, Toast.LENGTH_LONG).show();
        super.onActivityResult(requestCode, resultCode, data);
        }

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返回方：

![复制代码][copycode.gif]

Intent data = new Intent();
    data.setClass(SecondActivity.this, MainActivity.class);
    Bundle bundle = new Bundle();
    bundle.putString("name", "张无忌");
    bundle.putInt("age", 20);
    bundle.putFloat("weight", 120.5f);
    data.putExtras(bundle);
    setResult(250, data);
    finish();

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**启动Activity**

*上下文中，通过如下方法启动Activity*  
\*startActivity(Intent intent)：启动新的Activity  
\*startActivityForResult(Intent intent, int requestCode)：指定请求码启动新的Activity

如果使用startActivityForResult()启动Activity，则必须重写onActivityResult()方法，并且该方法第一个参数与requestCode相对应

**关闭Activity**

*上下文中，通过如下方法关闭Activity*  
\*finish()：关闭当前Activity  
\*finishActivity(int requestCode)：关闭以startActivity启动的Activity  
在调用finish()关闭当前Activity前，可以调用setResult(int resultCode)设置返回码。返回码在启动的Activity中通过onActivityResult()捕获

[copycode.gif]: /images/20220417/89c5ef5b148e44f1a1499b1a0c65a768.png