Android中数据的传递 _Android

归志宁无五亩园，读书本意在元元。这篇文章主要讲述Android中数据的传递相关的知识，希望能为你提供帮助。
android中当两个Activity需要有信息交互的时候，可以使用Intent。具体来说：
发送单一类型数据：

发送方： String data = "https://www.songbingjia.com/android/Hello SecondActivity"; Intent intent = new Intent(FirstActivity.this, SecondActivity.class); intent.putExtra("extra_data", data); startActivity(intent); #在onClick中调用接收方： Intentintent = getIntent(); String data = https://www.songbingjia.com/android/intent.getStringExtra("extra_data"); #可以在onCreate中读取

除了putExtra("key", value)/getStringExtra("key")之外, 根据传递的value的类型还有很多对，比如：

putExtra("key", intvalue)/getintExtra("key") putExtra("key", floatvalue)/getfloatExtra("key") putExtra("key", doublevalue)/getDoubleExtra("key")
putExtra("key", bundlevalue)/getBundleExtra("key")

...

发送多种数据类型的组合：
也可以用Bundle把很多数据类型（包括嵌套Bundle）放到Bundle中一并发送：

//sender
Bundle b = new Bundle(); b.putInt("age", 2); b.putString("data", "hello"); intent.putExtras(b); startActivity(intent);

//receiver
Intent i = getIntent(); Bundle b = i.getExtras(); int age = b.getInt("age"); String data = https://www.songbingjia.com/android/b.getString("data");

发送类对象：
方法1：Serializable
Serializable是java提供的序列化方法，优点是使用简单，一切由系统负责；缺点是速度稍慢。

public class User implements Serializable{ private String name; private Integer age; public String getName() { return name; }public void setName(String name) { this.name = name; }public Integer getAge() { return age; }public void setAge(Integer age) { this.age = age; }public User(String name, Integer age){ this.name = name; this.age = age; } }

//sender
intent.putExtra("user", (Serializable) new User("JM", 30));

//Receiver Intent i = getIntent(); User user = (User) i.getSerializableExtra("user"); textView.setText(String.format("name: %s, age: %s", user.getName(), user.getAge()));

方法2：Parcelable

public class User implements Parcelable{ private String name; private Integer age; public String getName() { return name; }public void setName(String name) { this.name = name; }public Integer getAge() { return age; }public void setAge(Integer age) { this.age = age; }public User(String name, Integer age){ this.name = name; this.age = age; }@Override public int describeContents() { return 0; }@Override public void writeToParcel(Parcel parcel, int i) { //write all the fields that want to send parcel.writeString(getName()); parcel.writeInt(getAge()); }public static final Creator< User> CREATOR = new Creator< User> () { @Override public User createFromParcel(Parcel parcel) { return new User(parcel.readString(), parcel.readInt()); }@Override public User[] newArray(int i) { return new User[i]; } }; }

//Sender intent.putExtra("user", (Parcelable) new User("JM", 30)); startActivity(intent);

//Receiver User user = (User) i.getParcelableExtra("user"); textView.setText(String.format("name: %s, age: %s", user.getName(), user.getAge()));

如果在User中有多个同类型字段，比如String，可以用Bundle来实现：

@Override public void writeToParcel(Parcel parcel, int i) { //write all the fields that want to send //parcel.writeString(getName()); //parcel.writeInt(getAge()); Bundle b = new Bundle(); b.putString("name", getName()); b.putInt("age", getAge()); parcel.writeBundle(b); }public static final Creator< User> CREATOR = new Creator< User> () { @Override public User createFromParcel(Parcel parcel) { //return new User(parcel.readString(), parcel.readInt()); Bundle b = parcel.readBundle(); return new User(b.getString("name"), b.getInt("age")); }@Override public User[] newArray(int i) { return new User[i]; } };

从别的Activity得到返回结果：
启动端：