startActivityForResult用法詳解

發(fā)表時(shí)間：2020-10-19

發(fā)布人：葵宇科技

瀏覽次數(shù)：60

一、如不雅想在Activity中獲得新打開(kāi)Activity 封閉后返回的數(shù)據(jù)，須要應(yīng)用體系供給的startActivityForResult(Intent intent, int requestCode)辦法打開(kāi)新的Activity，新的Activity 封閉后會(huì)向前面的Activity傳回?cái)?shù)據(jù)，為了獲得傳回的數(shù)據(jù)，必須在前面的Activity中重寫onActivityResult(int requestCode, int resultCode, Intent data)辦法。
[img]http://common.cnblogs.com/images/copycode.gif


package com.ljq.activitys;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;

public class MainActivity extends Activity {
    private final static String TAG="MainActivity";
    
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        Button btnOpen=(Button)this.findViewById(R.id.btnOpen);
        btnOpen.setOnClickListener(new View.OnClickListener(){
            public void onClick(View v) {
                //獲得新打開(kāi)Activity封閉后返回的數(shù)據(jù)
                //第二個(gè)參數(shù)為請(qǐng)求碼，可以根據(jù)營(yíng)業(yè)需求本身編號(hào)
                startActivityForResult(new Intent(MainActivity.this, OtherActivity.class), 1);
            }
        });
    }
    
    /**
     * 為了獲得傳回的數(shù)據(jù)，必須在前面的Activity中（指MainActivity類）重寫onActivityResult辦法
     * 
     * requestCode 請(qǐng)求碼，即調(diào)用startActivityForResult()傳遞以前的值
     * resultCode 結(jié)不雅碼，結(jié)不雅碼用于標(biāo)識(shí)返回?cái)?shù)據(jù)來(lái)自哪個(gè)新Activity
     */
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        String result = data.getExtras().getString("result");//獲得新Activity 封閉后返回的數(shù)據(jù)
        Log.i(TAG, result);
    }
}

[img]http://common.cnblogs.com/images/copycode.gif
當(dāng)新Activity封閉后，新Activity返回的數(shù)據(jù)經(jīng)由過(guò)程Intent進(jìn)行傳遞，android平臺(tái)會(huì)調(diào)用前面Activity 的onActivityResult()辦法，把存放了返回?cái)?shù)據(jù)的Intent作為第三個(gè)輸入?yún)?shù)傳入，在onActivityResult()辦法中應(yīng)用第三個(gè)輸入?yún)?shù)可以掏出新Activity返回的數(shù)據(jù)。

二、應(yīng)用startActivityForResult(Intent intent, int requestCode)辦法打開(kāi)新的Activity，新Activity封閉前須要向前面的Activity返回?cái)?shù)據(jù)須要應(yīng)用體系供給的setResult(int resultCode, Intent data)辦法實(shí)現(xiàn)：
[img]http://common.cnblogs.com/images/copycode.gif


package com.ljq.activitys;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class OtherActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.other);

        Button btnClose=(Button)findViewById(R.id.btnClose);
        btnClose.setOnClickListener(new View.OnClickListener(){
            public void onClick(View v) {
                //數(shù)據(jù)是應(yīng)用Intent返回
                Intent intent = new Intent();
                //把返回?cái)?shù)據(jù)存入Intent
                intent.putExtra("result", "My name is linjiqin");
                //設(shè)置返回?cái)?shù)據(jù)
                OtherActivity.this.setResult(RESULT_OK, intent);
                //封閉Activity
                OtherActivity.this.finish();
            }
        });
        
    }

}

[img]http://common.cnblogs.com/images/copycode.gif
setResult()辦法的第一個(gè)參數(shù)值可以根據(jù)營(yíng)業(yè)須要本身定義，膳綾擎代碼中應(yīng)用到的RESULT_OK是體系A(chǔ)ctivity類定義的一個(gè)常量，值為-1，代碼片段如下：
public class android.app.Activity extends ......{
public static final int RESULT_CANCELED = 0;
public static final int RESULT_OK = -1;
public static final int RESULT_FIRST_USER = 1;
}
運(yùn)行結(jié)不雅
[img]http://pic002.cnblogs.com/images/2011/270324/2011060315103017.png      [img]http://pic002.cnblogs.com/images/2011/270324/2011060315103953.png
解釋：當(dāng)點(diǎn)擊“打開(kāi)新的Activity”按鈕，會(huì)跳轉(zhuǎn)到“我是新打開(kāi)的Activity”頁(yè)面；
        當(dāng)點(diǎn)擊“封閉”按鈕，封閉當(dāng)前頁(yè)面，同時(shí)跳轉(zhuǎn)到“我是舊的Activity”頁(yè)面，且會(huì)傳遞result參數(shù)給前一個(gè)Activity


請(qǐng)求碼的感化
應(yīng)用startActivityForResult(Intent intent, int requestCode)辦法打開(kāi)新的Activity，我們須要為startActivityForResult()辦法傳入一個(gè)請(qǐng)求碼(第二個(gè)參數(shù))。請(qǐng)求碼的值是根據(jù)營(yíng)業(yè)須要由自已設(shè)定，用于標(biāo)識(shí)請(qǐng)求來(lái)源。例如：一個(gè)Activity有兩個(gè)按鈕，點(diǎn)擊這兩個(gè)按鈕都邑打開(kāi)同一個(gè)Activity，不管是那個(gè)按鈕打開(kāi)新Activity，當(dāng)這個(gè)新Activity封閉后，體系都邑調(diào)用前面Activity的onActivityResult(int requestCode, int resultCode, Intent data)辦法。在onActivityResult()辦法如不雅須要知道新Activity是由那個(gè)按鈕打開(kāi)的，并且要做出響應(yīng)的營(yíng)業(yè)處理，這時(shí)可以如許做：
@Override public void onCreate(Bundle savedInstanceState) {
        ....
        button1.setOnClickListener(new View.OnClickListener(){
            public void onClick(View v) {
                startActivityForResult (new Intent(MainActivity.this, NewActivity.class), 1);
           }
        });
        button2.setOnClickListener(new View.OnClickListener(){
            public void onClick(View v) {
                 startActivityForResult (new Intent(MainActivity.this, NewActivity.class), 2);
            }
        });

       @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) {
               switch(requestCode){
                   case 1:
                   //來(lái)自按鈕1的請(qǐng)求，作響應(yīng)營(yíng)業(yè)處理
                   case 2:
                   //來(lái)自按鈕2的請(qǐng)求，作響應(yīng)營(yíng)業(yè)處理
                }
          }
}


結(jié)不雅碼的感化
在一個(gè)Activity中，可能會(huì)應(yīng)用startActivityForResult()辦法打開(kāi)多個(gè)不合的Activity處理不合的營(yíng)業(yè)，當(dāng)這些新Activity封閉后，體系都邑調(diào)用前面Activity的onActivityResult(int requestCode, int resultCode, Intent data)辦法。為了知道返回的數(shù)據(jù)來(lái)自于哪個(gè)新Activity，在onActivityResult()辦法中可以如許做(ResultActivity和NewActivity為要打開(kāi)的新Activity)：
public class ResultActivity extends Activity {
       .....
       ResultActivity.this.setResult(1, intent);
       ResultActivity.this.finish();
}
public class NewActivity extends Activity {
       ......
        NewActivity.this.setResult(2, intent);
        NewActivity.this.finish();
}
public class MainActivity extends Activity { // 在該Activity會(huì)打開(kāi)ResultActivity和NewActivity
       @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) {
               switch(resultCode){
                   case 1:
                   // ResultActivity的返回?cái)?shù)據(jù)
                   case 2:
                    // NewActivity的返回?cái)?shù)據(jù)
                }
          }
}