Android:Intent传递数据的几种类型和源码实现

public class Intent implements Parcelable, Cloneable { //... private String mAction;

private Uri mData;

private String mType;

private String mPackage;

private ComponentName mComponent;

private int mFlags;

private HashSet<String> mCategories;

private Bundle mExtras;

private Rect mSourceBounds;

转自：http://blog.csdn.net/annkie/article/details/8483253

Intent也是继承了Parcelable的接口。

个人理解，Intent应该只是一个数据参数的载体，真正将两个Acitivity/Service通信起来的是Binder接口(C/S架构)。

第一类:简单或基本数据类型

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Intent putExtra(String name, int[] value)

Intent putExtra(String name, float value)

Intent putExtra(String name, byte[] value)

Intent putExtra(String name, long[] value)

Intent putExtra(String name, float[] value)

Intent putExtra(String name, long value)

Intent putExtra(String name, String[] value)

Intent putExtra(String name, boolean value)

Intent putExtra(String name, boolean[] value)

Intent putExtra(String name, short value)

Intent putExtra(String name, double value)

Intent putExtra(String name, short[] value)

Intent putExtra(String name, String value)

Intent putExtra(String name, byte value)

Intent putExtra(String name, char[] value)

Intent putExtra(String name, CharSequence[] value)

本质上仍然是通过一个Bundle(private Bundle mExtras;)来实现：

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public Intent putExtra(String name, long value) {

if (mExtras == null) {

mExtras = new Bundle();

}

mExtras.putLong(name, value);

return this;

}

第二类:传递一个Bundle

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public Intent putExtra(String name, Bundle value) {

if (mExtras == null) {

mExtras = new Bundle();

}

mExtras.putBundle(name, value);

return this;

}

第三类：传递Serializable对象

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public Intent putExtra(String name, Serializable value) {

if (mExtras == null) {

mExtras = new Bundle();

}

mExtras.putSerializable(name, value);

return this;

}

第四类：Parcelable对象

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public Intent putExtra(String name, Parcelable value) {

if (mExtras == null) {

mExtras = new Bundle();

}

mExtras.putParcelable(name, value);

return this;

}

public Intent putExtra(String name, Parcelable[] value) {

if (mExtras == null) {

mExtras = new Bundle();

}

mExtras.putParcelableArray(name, value);

return this;

}

第五类：Intent

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public Intent putExtras(Intent src) {

if (src.mExtras != null) {

if (mExtras == null) {

mExtras = new Bundle(src.mExtras);

} else {

mExtras.putAll(src.mExtras);

}

}

return this;

}

归根结底都是通过Bundle来实现数据封装。而Bundle则是通过Map的数据结构来存储数据。

mMap = new HashMap<String, Object>();

mParcelledData

两者同时只有一个有效。

一旦unparcel以后，mParcelledData

的数据将被填充到mMap中，同时值为null。在writeToParcel和readFromParcel中则直接使用mParcelledData.此时一般通过IBinder关联两个进程的通信。

关于Bundle则是实现了Parcelable接口的类，通过上面提到的HashMap和一个Parcel来存储数据。

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public final class Bundle implements Parcelable, Cloneable {

private static final String LOG_TAG = "Bundle";

public static final Bundle EMPTY;

static {

EMPTY = new Bundle();

EMPTY.mMap = Collections.unmodifiableMap(new HashMap<String, Object>());

}

// Invariant - exactly one of mMap / mParcelledData will be null

// (except inside a call to unparcel)

/* package */ Map<String, Object> mMap = null;

/*

* If mParcelledData is non-null, then mMap will be null and the

* data are stored as a Parcel containing a Bundle. When the data

* are unparcelled, mParcelledData willbe set to null.

*/

/* package */ Parcel mParcelledData = null;

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public void putFloat(String key, float value) {

unparcel();//首先解析出mParcelledData到mMap

mMap.put(key, value);

}

/* package */ synchronized void unparcel() {

if (mParcelledData == null) {

return;

}

int N = mParcelledData.readInt();

if (N < 0) {

return;

}

if (mMap == null) {

mMap = new HashMap<String, Object>();

}

mParcelledData.readMapInternal(mMap, N, mClassLoader);

mParcelledData.recycle();

mParcelledData = null;//回收以后值为null

}