在Davilk中，给一个程序分配的内存依据机型厂商的不同，而不同。如今的大部分的是32M了。而在VM内部会把这些内存分成java使用的内存和 Native使用的内存，它们之间是不能共享的。就是说当你的Native内存用完了。如今Java又有空暇的内存。这时Native会又一次像VM申请，而不是直接使用java的。

比如上边的样例

explicit 3411K/6663K

external 24870K/26260K

假设这时须要创建一个2M的

Bitmap，

Native现有内存26260-24870=1390K<2048k,因此他就会向Vm申请内存，尽管java空暇的内存是

6663-3411=3252>2048,但这部分内存Native是不能使用。

可是你如今去申请2M的Native内存，VM会告诉你无法分配的，由于如今已使用的内存已经接近峰值了32M(26260+6663=32923 )，所以如今就会成force close 报OOM。

所以如今我们要检查我们的native内存的使用情况来避免OOM。

ps: http://stackoverflow.com/questions/2298208/how-to-discover-memory-usage-of-my-application-in-android#2299813

三、通过Android系统提供的Runtime类，运行adb 命令(top,procrank,ps...等命令)查询

内存耗用：VSS/RSS/PSS/USS
Terms
? VSS - Virtual Set Size 虚拟耗用内存（包括共享库占用的内存）
?

RSS - Resident Set Size 实际使用物理内存（包括共享库占用的内存）
? PSS - Proportional Set Size 实际使用的物理内存（比例分配共享库占用的内存）
? USS - Unique Set Size 进程独自占用的物理内存（不包括共享库占用的内存）
一般来说内存占用大小有例如以下规律：VSS >= RSS >= PSS >= USS

查看每一个进程及其内存状况

 private void getRunningAppProcessInfo() {mActivityManager = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);// 获得系统里正在执行的全部进程List<RunningAppProcessInfo> runningAppProcessesList = mActivityManager.getRunningAppProcesses();for (RunningAppProcessInfo runningAppProcessInfo : runningAppProcessesList) {// 进程ID号int pid = runningAppProcessInfo.pid;// 用户IDint uid = runningAppProcessInfo.uid;// 进程名String processName = runningAppProcessInfo.processName;// 占用的内存int[] pids = new int[] { pid };Debug.MemoryInfo[] memoryInfo = mActivityManager.getProcessMemoryInfo(pids);int memorySize = memoryInfo[0].dalvikPrivateDirty;st = st + "processName=" + processName + ",pid=" + pid + ",uid="+ uid + ",memorySize=" + memorySize + "kb" + "\n";System.out.println("processName=" + processName + ",pid=" + pid+ ",uid=" + uid + ",memorySize=" + memorySize + "kb");}}

查看总内存：

  public long getmem_TOLAL() {long mTotal;// /proc/meminfo读出的内核信息进行解释String path = "/proc/meminfo";String content = null;BufferedReader br = null;try {br = new BufferedReader(new FileReader(path), 8);String line;if ((line = br.readLine()) != null) {content = line;}} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();} finally {if (br != null) {try {br.close();} catch (IOException e) {e.printStackTrace();}}}// beginIndexint begin = content.indexOf(':');// endIndexint end = content.indexOf('k');// 截取字符串信息content = content.substring(begin + 1, end).trim();mTotal = Integer.parseInt(content);return mTotal;}

查看内存信息（该api较新）：

   public long getmem_UNUSED(Context mContext) {long MEM_UNUSED;// 得到ActivityManagerActivityManager am = (ActivityManager) mContext.getSystemService(Context.ACTIVITY_SERVICE);// 创建ActivityManager.MemoryInfo对象ActivityManager.MemoryInfo mi = new ActivityManager.MemoryInfo();am.getMemoryInfo(mi);textView3.setText("totalMen:" + mi.totalMem / 1024 + "\n"+ "threshold:" + mi.threshold / 1024 + "\n" + "availMem:"+ mi.availMem / 1024 + "\n");// 取得剩余的内存空间MEM_UNUSED = mi.availMem / 1024;return MEM_UNUSED;}

查看app内存：

    ActivityManager manager = (ActivityManager) getSystemService(ACTIVITY_SERVICE);int i=manager.getMemoryClass();textView.setText("\n"+"app:"+i);

实例1

int cnt=0;

final static int kBufferMinSize=1000;

final static int kBufferMaxSize=2000;

StringBuffer strBuffer=new StringBuffer(kBufferMinSize);

StringBuffer strBuffer2=new StringBuffer(kBufferMinSize);

StringBuffer strBuffer3=new StringBuffer(kBufferMinSize);

StringBuffer strBufferNativePss=new StringBuffer(kBufferMinSize);

StringBuffer strBufferDalvikPss=new StringBuffer(kBufferMinSize);

StringBuffer strBufferOtherPss=new StringBuffer(kBufferMinSize);

Debug.MemoryInfo memoryInfo=new Debug.MemoryInfo();

final static String tag="robin";

void printMemory()

{

long totalMemory=Runtime.getRuntime().totalMemory();

long freeMemory=Runtime.getRuntime().freeMemory();

long usedMemory=(totalMemory-freeMemory)>>10;

totalMemory=totalMemory>>10;

freeMemory=freeMemory>>10;

if(strBuffer.length()>kBufferMaxSize)

{

strBuffer.delete(0,strBuffer.length());

strBuffer2.delete(0,strBuffer2.length());

strBuffer3.delete(0,strBuffer3.length());

strBufferNativePss.delete(0,strBufferNativePss.length());

strBufferDalvikPss.delete(0,strBufferDalvikPss.length());

}

strBuffer.append(usedMemory+",");

strBuffer2.append(totalMemory+",");

strBuffer3.append((Debug.getNativeHeapSize()>>10)+",");

Debug.getMemoryInfo(memoryInfo);

strBufferNativePss.append((memoryInfo.nativePss)+",");

strBufferDalvikPss.append((memoryInfo.dalvikPss)+",");

if(cnt++==0)

{

Log.i(tag,"usedMemory:"+strBuffer.toString());

Log.i(tag,"totalMemory:"+strBuffer2.toString());

Log.i(tag,"NativeHeapSize:"+strBuffer3.toString());

Log.i(tag,"Native PSS:"+strBufferNativePss.toString());

Log.i(tag,"Dalvik PSS:"+strBufferDalvikPss.toString());

}

}