一起Talk Android吧（第二百四十一回：Android中Activity之间的数据传递三）

各位看官们大家好，上一回中咱们说的是Android中Activity之间数据传递的例子,这一回咱们继续说该例子。闲话休提，言归正转。让我们一起Talk Android吧！

看官们，这一回可以看作是Activity之间跳转和数据传递的大结局，我们整理了所有的流程，然后通过完整的代码来演示。下面是具体的代码请大家参考：

package com.example.talk8.blogappall;

import android.content.Intent;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.widget.Button;

//介绍Activity之间，以及Fragment之间的交互和数据传递
public class ActivityA extends AppCompatActivity {
    
    
    private Button mBtStartActB;
    private Button mBtStartActBForData;
    private Intent mIntent = null;
    private int REQUEST_CODE = 1;
    public static final String KEY = "value_key";
    private static final String TAG = "DataStorage";

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

        mBtStartActB =(Button)findViewById(R.id.start_activity_b);
        mBtStartActBForData =(Button)findViewById(R.id.start_activity_b_for_data);

        mBtStartActB.setOnClickListener(v -> startActivityB());
        mBtStartActBForData.setOnClickListener(v->startActivityBForData());
    }

    private void startActivityB() {
    
    
        int value = 5;
        if(mIntent != null)
            mIntent = null;

        //send Data to ActivityB
        mIntent = new Intent(ActivityA.this,ActivityB.class);
        mIntent.putExtra(KEY,value);
        startActivity(mIntent);
        Log.i(TAG, "startActivityB and send Data: "+value);
    }
    //want to get data from ActivityB
    private void startActivityBForData() {
    
    
        if(mIntent != null)
            mIntent = null;

        mIntent = new Intent(ActivityA.this,ActivityB.class);
        startActivityForResult(mIntent,REQUEST_CODE);
        Log.i(TAG, "startActivityB For getting Data: ");
    }

    //get data from ActivityB
    @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
    
    
        //注意：确认数据来源
        if(requestCode == REQUEST_CODE && resultCode == RESULT_OK) {
    
    
           int result = data.getExtras().getInt(KEY);
            Log.i(TAG, "onActivityResult: ActivityA get data from ActivityB : "+result);
        }else {
    
    
            Log.i(TAG, "onActivityResult: it is not a effective data");
        }
    }
}

package com.example.talk8.blogappall;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;

public class ActivityB extends AppCompatActivity {
    
    
    private static final String TAG = "DataStorage";
    private Intent mIntent;
    private int value;

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

        //get data from ActivityA
        mIntent = getIntent();

        if(mIntent != null ) {
    
    
            if (mIntent.hasExtra(ActivityA.KEY)) {
    
    
                //get data from ActivityA
                value = mIntent.getIntExtra(ActivityA.KEY,0);
                if(value != 0) {
    
    
                    Log.i(TAG, "onCreate: ActivityB get Data from ActivityA: "+value);
                }else {
    
    
                    Log.i(TAG, "onCreate: ActivityB get Data is null");
                }
            } else {
    
    
                //send data to ActivityA
                value = 9;
                Log.i(TAG, "onCreate: ActivityB send Data: "+value+" to ActivityA ");
                mIntent = null;
                mIntent = new Intent();
                mIntent.putExtra(ActivityA.KEY,value);
                setResult(RESULT_OK,mIntent);
            }
        }
    }
}

在代码中我们主要做了优化并且添加了log和注释，下面是程序的运行结果，请大家参考：

 //点击按钮从A跳转到B，并且发送数据5给B
 I/DataStorage: startActivityB and send Data: 5
 //B收到了A传递来的数据5
 I/DataStorage: onCreate: ActivityB get Data from ActivityA: 5
 //点击按钮从A跳转到B，并且请求B发送数据给A
 I/DataStorage: startActivityB For getting Data:
 //跳转到B后，B发送数据9给A
 I/DataStorage: onCreate: ActivityB send Data: 9 to ActivityA
 //A收到了B传递来的数据9
 I/DataStorage: ActivityA get data from ActivityB : 9

各位看官，关于Android中Activity之间数据传递的例子咱们就介绍到这里，欲知后面还有什么例子，且听下回分解！