android之Activity回传数据

约定:当Activity发生跳转时将原来的Activity成为父Activity,将新出现的Activity成为子Activity。

情景设置

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下面是个发短信的Activity

当我们点击图中的+按钮后会跳转到联系人界面

在联系人界面选择某个联系人后，比如联系人ccc，联系人界面消失并回到发短信界面。

这其中设计到了Activity的跳转以及数据回传

过程分析

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当在父Activity中进行了某些操作后，产生了子Activity。然后我们在子Activity又进行了一些操作，同时希望父Activity知道这些操作。那么在子Activity退出时将数据封装到一个对象中，而在父Activity中接受回传的这个对象。

编程实现

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布局文件

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">
        <EditText
            android:id="@+id/contact"
            android:layout_weight="1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:hint="请输入联系人"/>
        <Button
            android:id="@+id/add"
            android:layout_weight="0"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="+"
            android:onClick="click"/>
    </LinearLayout>
    <EditText
        android:id="@+id/content"
        android:gravity="top"
        android:layout_weight="1"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:hint="请输入消息内容"/>
    <Button
        android:id="@+id/reply"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="快捷回复"
        android:onClick="click1"/>
    <Button
        android:id="@+id/send"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="发送短信"/>
</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">
    <ListView
        android:id="@+id/lv"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

    </ListView>
</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">
<TextView
    android:id="@+id/item"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:textSize="25sp"/>
</LinearLayout>

java代码

package xidian.dy.com.chujia;

import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.EditText;

public class MainActivity extends AppCompatActivity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

    }

    //点击事件发生时切换至联系人Activity
    public void click(View v) {
        Intent intent = new Intent();
        intent.setClass(this, ContactActivity.class);
        intent.addCategory(Intent.CATEGORY_DEFAULT);
        //设置子Activity在销毁时会有数据返回
        //10为子Activity的编号
        startActivityForResult(intent, 10);
    }

    public void click1(View v) {
        Intent intent = new Intent();
        intent.setClass(this, ReplyActivity.class);
        intent.addCategory(Intent.CATEGORY_DEFAULT);
        startActivityForResult(intent, 20);
    }

    //当子Activity被销毁的后,父Activity会回到前台,这时候该方法就会被调用
    //来获取子Activity返回给父Activity的数据

    /**
     *
     * @param requestCode 在创建子Activity时为其指定的的编号
     * @param resultCode  返回的数据类型(从功能上划分),一个子Activity可能返回种数据类型(如联系人姓名/联系人电话)
     * @param data 返回的数据
     */
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        //获取返回的数据
        String name = data.getStringExtra("name");
        //判断是哪个Activity返回的
        if(requestCode == 10) {
            EditText et = (EditText) findViewById(R.id.contact);
            if(et != null)
                et.setText(name);
        }
        else if(requestCode == 20) {
            EditText et = (EditText) findViewById(R.id.content);
            if(et != null)
                et.setText(name);
        }
    }
}

package xidian.dy.com.chujia;

import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;

/**
 * Created by dy on 2016/7/8.
 */
public class ContactActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_contact);
        ListView listView = (ListView) findViewById(R.id.lv);
        final String[] strs = new String[]{"aaa", "bbb", "ccc","ddd","eee","fff","ggg"};
        if(listView != null) {
            listView.setAdapter(new ArrayAdapter<>(this, R.layout.item_list, R.id.item, strs));
            listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                @Override
                public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

                    Intent intent = new Intent();
                    intent.putExtra("name", strs[position]);
                    setResult(1, intent);
                    finish();
                }
            });
        }
    }
}

package xidian.dy.com.chujia;

import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;

/**
 * Created by dy on 2016/7/8.
 */
public class ReplyActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_contact);
        ListView listView = (ListView) findViewById(R.id.lv);
        final String[] strs = new String[]{"你好", "在吗", "大海"};
        if(listView != null){
            //填充布局
            listView.setAdapter(new ArrayAdapter<>(this, R.layout.item_list, R.id.item, strs));
            //设置监听器
            listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                @Override
                public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                    Intent data = new Intent();
                    data.putExtra("name", strs[position]);
                    //设置数据类型
                    setResult(1, data);
                    //销毁对象
                    finish();
                }
            });
        }
    }
}

清单文件 

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="xidian.dy.com.chujia">
    <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity
            android:name=".MainActivity"
            android:label="主界面">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".ContactActivity">
            <intent-filter>
                <action android:name="android.intent.action.contact"/>
                <category android:name="android.intent.category.DEFAULT"/>
            </intent-filter>
        </activity>
        <activity android:name=".ReplyActivity">
            <intent-filter>
                <action android:name="android.intent.action.replay"/>
                <category android:name="android.intent.category.DEFAULT"/>
            </intent-filter>
        </activity>
    </application>
</manifest>