PID 指进程ID.
PID是进程的身份标识，程序一旦运行，就会给应用分配一个独一无二的PID(ps:一个应用可能包含多个进程，每个进程有唯一的一个PID)
进程终止后PID会被系统收回，再次打开应用，会重新分配一个PID（新进程的PID一般比之前的号要大）
命令：adb shell+ps|grep(图1)或adb shell ps （图2）
图1：
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图2：
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UID 指用户ID.
UID在linux中就是用户的ID，表明时哪个用户运行了这个程序，主要用于权限的管理。而在android 中又有所不同，因为android为单用户系统，这时UID 便被赋予了新的使命，数据共享，为了实现数据共享，android为每个应用几乎都分配了不同的UID，不像传统的linux，每个用户相同就为之分配相同的UID。（当然这也就表明了一个问题，android只能时单用户系统，在设计之初就被他们的工程师给阉割了多用户），使之成了数据共享的工具。
命令：adb shellcat/proc/PID号/status（图3）
图3
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【Visual|Android中的PID,UID,TID】因此在android中PID，和UID都是用来识别应用程序的身份的，但UID是为了不同的程序来使用共享的数据。
package com.inanwong.main;
import android.app.Activity;
import android.os.Bundle;
import android.os.Process;
import android.util.Log;
public class MainActivity extends Activity {
private static final String TAG = MainActivity.class.getSimpleName();
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
/**
* Returns the identifier of this process's user.
*/
Log.e(TAG, "Process.myUid() = " + Process.myUid());
/**
* Returns the identifier of this process, which can be used with
* killProcess and sendSignal.
*/
Log.e(TAG, "Process.myPid() = " + Process.myPid());
/**
* Returns the identifier of the calling thread, which be used with
* setThreadPriority(int, int).
*/
Log.e(TAG, "Process.myTid() = " + Process.myTid());
/**
* Returns the thread's identifier. The ID is a positive long generated
* on thread creation, is unique to the thread, and doesn't change
* during the lifetime of the thread;
the ID may be reused after the
* thread has been terminated.
*/
Log.e(TAG, "Thread.currentThread().getId() = "
+ Thread.currentThread().getId());
Log.e(TAG, "getMainLooper().getThread().getId() = "
+ getMainLooper().getThread().getId());
/**
* Returns the thread's identifier. The ID is a positive long generated
* on thread creation, is unique to the thread, and doesn't change
* during the lifetime of the thread;
the ID may be reused after the
* thread has been terminated.
*/
Log.e(TAG,
"((getApplication().getMainLooper()).getThread()).getId() = "
+ ((getApplication().getMainLooper()).getThread())
.getId());
/**
* Return the identifier of the task this activity is in. This
* identifier will remain the same for the lifetime of the activity.
*/
Log.e(TAG, "getTaskId() = " + getTaskId());
/**
* The kernel user-ID that has been assigned to this application;
* currently this is not a unique ID (multiple applications can have the
* same uid).
*/
Log.e(TAG, "getApplicationInfo().uid = " + getApplicationInfo().uid);
/**
* The name of the process this application should run in. From the
* "process" attribute or, if not set, the same as packageName.
*/
Log.e(TAG, "getApplicationInfo().processName = "
+ getApplicationInfo().processName);
new Thread(new Runnable() {
@Override
public void run() {
// TODO Auto-generated method stub
Log.e(TAG, "Thread.currentThread().getId() = "
+ Thread.currentThread().getId());
}
}).start();
}
}Log information:
10-12 01:57:30.885: ERROR/MainActivity(253): Process.myUid() = 10032
10-12 01:57:30.885: ERROR/MainActivity(253): Process.myPid() = 253
10-12 01:57:30.885: ERROR/MainActivity(253): Process.myTid() = 253
10-12 01:57:30.885: ERROR/MainActivity(253): Thread.currentThread().getId() = 1
10-12 01:57:30.885: ERROR/MainActivity(253): getMainLooper().getThread().getId() = 1
10-12 01:57:30.885: ERROR/MainActivity(253): ((getApplication().getMainLooper()).getThread()).getId() = 1
10-12 01:57:30.885: ERROR/MainActivity(253): getTaskId() = 3
10-12 01:57:30.885: ERROR/MainActivity(253): getApplicationInfo().uid = 10032
10-12 01:57:30.885: ERROR/MainActivity(253): getApplicationInfo().processName = com.inanwong.main
10-12 01:57:30.914: ERROR/MainActivity(253): Thread.currentThread().getId() = 8
