Android软件开发

有很多时候都需要在不同的Activity之间传递数据。
实现方法有很多，可以用Bundle来传递，也可以用给Intent用putExtra传递附加参数。
当然也可以传递自定义类的对象。为了让自定义类可以在Activity之间传递，必须符合一些条件。常用的方法是自定义类实现Parcelable接口或Serializable接口。Android中建议实现Parcelable。
下面例子中两种方法都有例子。
传递Parcelable过去，再传递Serializable回来。

1. import android.os.Parcel;   
2. import android.os.Parcelable;   
3.   
4. public class WeightParcelable implements Parcelable {   
5.     private String sex;   
6.     private double height;   
7. //必须的空构造器，因为下面有一个私有的构造器，否则不能new对象   
8.     public WeightParcelable() {   
9.   
10.     }   
11.   
12.     public String getSex() {   
13.         return sex;   
14.     }   
15.   
16.     public void setSex(String sex) {   
17.         this.sex = sex;   
18.     }   
19.   
20.     public double getHeight() {   
21.         return height;   
22.     }   
23.   
24.     public void setHeight(double height) {   
25.         this.height = height;   
26.     }   
27.   
28.     @Override  
29.     public int describeContents() {   
30.         return 0;   
31.     }   
32. //需要覆盖的方法   
33.     @Override  
34.     public void writeToParcel(Parcel out, int flags) {   
35.         out.writeString(sex);   
36.         out.writeDouble(height);   
37.     }   
38. //关键的事情   
39.     public static final Parcelable.Creator<WeightParcelable> CREATOR = new Parcelable.Creator<WeightParcelable>() {   
40.         public WeightParcelable createFromParcel(Parcel in) {   
41.             return new WeightParcelable(in);   
42.         }   
43.   
44.         public WeightParcelable[] newArray(int size) {   
45.             return new WeightParcelable[size];   
46.         }   
47.     };   
48. //   
49.     private WeightParcelable(Parcel in) {   
50.         sex = in.readString();   
51.         height = in.readDouble();   
52.     }   
53. }  

import android.os.Parcel; import android.os.Parcelable; public class WeightParcelable implements Parcelable { private String sex; private double height; //必须的空构造器，因为下面有一个私有的构造器，否则不能new对象 public WeightParcelable() { } public String getSex() { return sex; } public void setSex(String sex) { this.sex = sex; } public double getHeight() { return height; } public void setHeight(double height) { this.height = height; } @Override public int describeContents() { return 0; } //需要覆盖的方法 @Override public void writeToParcel(Parcel out, int flags) { out.writeString(sex); out.writeDouble(height); } //关键的事情 public static final Parcelable.Creator<WeightParcelable> CREATOR = new Parcelable.Creator<WeightParcelable>() { public WeightParcelable createFromParcel(Parcel in) { return new WeightParcelable(in); } public WeightParcelable[] newArray(int size) { return new WeightParcelable[size]; } }; // private WeightParcelable(Parcel in) { sex = in.readString(); height = in.readDouble(); } }

HeightSerializable.java

import java.io.Serializable; public class HeightSerializable implements Serializable { private static final long serialVersionUID = 8502706820090766507L; private String sex; private double weight; public String getSex() { return sex; } public void setSex(String sex) { this.sex = sex; } public double getWeight() { return weight; } public void setWeight(double weight) { this.weight = weight; } }

EX03_10.java

import android.app.Activity; import android.content.Intent; import android.os.Bundle; import android.util.Log; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.widget.RadioButton; import android.widget.TextView; public class EX03_10 extends Activity { public static final String parcelableKey = "irdc.ex03_10.parcelableKey"; public static final String seralizableKey = "irdc.ex03_10.seralizableKey"; private static final String TAG = "EX03_10"; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); Button b1 = (Button) findViewById(R.id.button1); b1.setOnClickListener(new Button.OnClickListener() { public void onClick(View v) { EditText et = (EditText) findViewById(R.id.height); double height = Double.parseDouble(et.getText().toString()); String sex = ""; RadioButton rb1 = (RadioButton) findViewById(R.id.sex1); if (rb1.isChecked()) { sex = "M"; } else { sex = "F"; } Intent intent = new Intent(); intent.setClass(EX03_10.this, EX03_10_1.class); Bundle bundle = new Bundle(); WeightParcelable wp = new WeightParcelable(); wp.setSex(sex); wp.setHeight((int) height); bundle.putParcelable(parcelableKey, wp); intent.putExtras(bundle); //注意这里 startActivityForResult(intent, 1); } }); } //这个是关键 @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { Log.d(TAG, "onActivityResult requestCode=" + requestCode + " resultCode= " + resultCode + " data == null[" + (data == null) + "]"); super.onActivityResult(requestCode, resultCode, data); if (requestCode == 1) { if (resultCode == RESULT_OK) { try { HeightSerializable hs = (HeightSerializable) data .getSerializableExtra(seralizableKey); TextView textView4 = (TextView) findViewById(R.id.text4); textView4.setText("性别：" + hs.getSex() + "\n标准体重:" + hs.getWeight()); } catch (Exception e) { e.printStackTrace(); } } } } }

EX03_10_1.java