第五章 模拟跳转充值界面以及requestCode和resultCode的解释 2.8

package com.example.infotransmission2;

import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;

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

/**
 * 数据回传
 * 点击充值按钮，跳转到第二个界面进行充值
 * 第二个界面进行充值，充值完成以后告诉第一个界面结果，包括充值成功或者失败
 *
 */
public class MainActivity extends AppCompatActivity {

    private Button mBtnRecharge;
    private TextView mTextPayResult;
    private static int PAY_REQUEST_CODE = 1;

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

        // Refactor-Extract Method
        initView();

        initListener();
    }

    private void initListener() {
        mBtnRecharge.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // 设置一个点击事件,跳转到第二个界面进行充值
                Intent intent = new Intent(MainActivity.this, PayActivity.class);
                // 第一步,使用startActivityForResult代替原来的startActivity,表明跳转到别的页面后(该界面与requestCode绑定),
                // 等待该界面的相关返回码
                startActivityForResult(intent,1);
            }
        });
    }

    /**
     * 第二步,复写方法,返回的结果就会在这里回调
     * @param requestCode
     * @param resultCode
     * @param data
     */
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        // 通过requestCode来判断返回的Activity是哪一个
        if (requestCode == PAY_REQUEST_CODE) {
            String resultContent = null;
            if (resultCode == 2) {
                // 充值成功
                resultContent = data.getStringExtra("resultContent");
            }
            else if(resultCode == 3){
                // 充值失败
                resultContent = data.getStringExtra("resultContent");
            }
            mTextPayResult.setText(resultContent);
        }
    }

    /**
     * 初始化控件
     */
    private void initView() {
        mBtnRecharge = (Button) this.findViewById(R.id.btn_recharge);
        mTextPayResult = (TextView) this.findViewById(R.id.pay_result);
    }
}

 1 package com.example.infotransmission2;  2  3 import androidx.appcompat.app.AppCompatActivity;  4  5 import android.content.Intent;  6 import android.os.Bundle;  7 import android.text.TextUtils;  8 import android.view.View;  9 import android.widget.Button; 10 import android.widget.EditText; 11 import android.widget.Toast; 12 13 public class PayActivity extends AppCompatActivity { 14 15 private EditText mEditInput; 16 private Button mBtnChargein; 17 private Button mBtnCancelCharge; 18 19  @Override 20 protected void onCreate(Bundle savedInstanceState) { 21 super.onCreate(savedInstanceState); 22  setContentView(R.layout.activity_pay); 23 24  initView(); 25 26  initListener(); 27  } 28 29 private void initListener() { 30 mBtnCancelCharge.setOnClickListener(new View.OnClickListener() { 31  @Override 32 public void onClick(View v) { 33  handlerCancel(); 34  } 35  }); 36 37 mBtnChargein.setOnClickListener(new View.OnClickListener() { 38  @Override 39 public void onClick(View v) { 40  handlerPay(); 41  } 42  }); 43  } 44 45 private void handlerCancel() { 46 Intent intent = new Intent(); 47 intent.putExtra("resultContent", "充值失败!"); 48 // 将该intent与设定的resultCode值相绑定 49 setResult(3, intent); 50  finish(); 51  } 52 53 private void handlerPay() { 54 String payNumber = mEditInput.getText().toString().trim(); 55 if (TextUtils.isEmpty(payNumber)) { 56 Toast.makeText(this, "请输入充值金额", Toast.LENGTH_SHORT).show(); 57 return; 58  } 59 60 // 进行充值(模拟,需要网络编程) 61 // 将该intent与设定的resultCode值相绑定 62 Intent intent = new Intent(); 63 intent.putExtra("resultContent", "充值成功!"); 64 setResult(2, intent); 65  finish(); 66  } 67 68 private void initView() { 69 mEditInput = (EditText) this.findViewById(R.id.edit_input); 70 mBtnChargein = (Button) this.findViewById(R.id.btn_chargein); 71 mBtnCancelCharge = (Button) this.findViewById(R.id.btn_cancelCharge); 72  } 73 74 }

<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity" android:orientation="vertical"> <Button android:layout_width="match_parent" android:layout_height="wrap_content" android:text="点击充值" android:id="@+id/btn_recharge"/> <TextView android:layout_width="match_parent" android:layout_height="match_parent" android:id="@+id/pay_result"/> </LinearLayout>

 1 <?xml version="1.0" encoding="utf-8"?>  2 <LinearLayout  3 xmlns:android="http://schemas.android.com/apk/res/android"  4  xmlns:app="http://schemas.android.com/apk/res-auto"  5  xmlns:tools="http://schemas.android.com/tools"  6  android:layout_width="match_parent"  7  android:layout_height="match_parent"  8  tools:context=".PayActivity"  9  android:orientation="vertical"> 10 11 <EditText 12 android:layout_width="match_parent" 13  android:layout_height="wrap_content" 14  android:hint="请输入充值金额" 15  android:id="@+id/edit_input" 16  android:inputType="number" 17  android:textSize="30sp"/> 18 19 <Button 20 android:layout_width="match_parent" 21  android:layout_height="wrap_content" 22  android:id="@+id/btn_chargein" 23  android:text="确定充值"/> 24 25 <Button 26 android:layout_width="match_parent" 27  android:layout_height="wrap_content" 28  android:text="取消充值" 29  android:id="@+id/btn_cancelCharge"/> 30 31 </LinearLayout>