下面列出了java.io.RandomAccessFile#readLine ( ) 实例代码，或者点击链接到github查看源代码，也可以在右侧发表评论。
public int printCpuUsages()
{
try
{
RandomAccessFile reader = new RandomAccessFile("/proc/stat", "r");
String load = reader.readLine();
while (load != null)
{
Log.d("CPU", "CPU usage: " + load);
load = reader.readLine();
}
}
catch (IOException ex)
{
// ex.printStackTrace();
return 0;
}
return 0;
}
/**
* Run until interrupted.
*/
public void run() {
try {
while (!me.isInterrupted()) {
File f_pipe = new File(fileName);
RandomAccessFile raf = new RandomAccessFile(f_pipe, "r");//p.1
String line = null;
for (; ; ) {
line = raf.readLine();
//Take care to check the line -
//it is null when the pipe has no more available data.
if (line != null) {
handler.handle(line);
} else {
break; //stop reading loop
}
}
}
} catch (Exception error) {
error.printStackTrace();
}
}
private static long findRDFNameSpaceEnd(RandomAccessFile file)
throws IOException {
long filePosition = 0;
String line;
int count = 0;
while ((line = file.readLine()) != null) {
if (line.trim().startsWith("<rdf:"))
count++;
if (count == 2)
break;
filePosition = file.getFilePointer();
}
return filePosition;
}
private static long findRDFNameSpaceEnd(RandomAccessFile file)
throws IOException {
long filePosition = 0;
String line;
int count = 0;
while ((line = file.readLine()) != null) {
if (line.trim().startsWith("<rdf:"))
count++;
if (count == 2)
break;
filePosition = file.getFilePointer();
}
return filePosition;
}
public static synchronized long[] readUsagePoint() {
long idle = 0;
long cpu = 0;
try {
RandomAccessFile reader = new RandomAccessFile("/proc/stat", "r");
String load = reader.readLine();
String[] tokens = load.split(" ");
for (int i = 2; i <= 8; i++) {
// 5 index has idle value
if (i == 5) {
idle = Long.parseLong(tokens[i]);
continue;
}
cpu += Long.parseLong(tokens[i]);
}
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
return new long[]{idle, cpu};
}
private static long findClosingRDFBracket(RandomAccessFile file)
throws IOException {
long length = file.length();
file.seek((long) (length * 0.9));
long lastLinePosition = -1;
String lastLine = "";
while (!lastLine.trim().equals("</rdf:RDF>")) {
lastLinePosition = file.getFilePointer();
lastLine = file.readLine();
if (lastLine == null)
throw new IOException(
"Malformed RDF, last line is not an RDF closing bracket: "
+ lastLine);
}
return lastLinePosition;
}
/**
* Read a line from the index
* @param pos
* @param expected
* @throws IOException
*/
protected void readLineFomIndex(final RandomAccessFile file, final FileLineIndex fli,
final long lineNumber, final String expected) throws IOException {
final long pos = fli.locateLine(lineNumber);
file.seek(pos);
final String line = file.readLine();
Assert.assertEquals(expected, line);
}
/**
* Returns CPU usage info. Careful using this it's CPU intensive by itself!
* @return Percentage
*/
private float getCPU() {
try {
RandomAccessFile reader = new RandomAccessFile("/proc/stat", "r");
String load = reader.readLine();
String[] toks = load.split(" ");
long idle1 = Long.parseLong(toks[5]);
long cpu1 = Long.parseLong(toks[2]) + Long.parseLong(toks[3]) + Long.parseLong(toks[4])
+ Long.parseLong(toks[6]) + Long.parseLong(toks[7]) + Long.parseLong(toks[8]);
try {
Thread.sleep(360);
} catch (Exception e) {}
reader.seek(0);
load = reader.readLine();
reader.close();
toks = load.split(" ");
long idle2 = Long.parseLong(toks[5]);
long cpu2 = Long.parseLong(toks[2]) + Long.parseLong(toks[3]) + Long.parseLong(toks[4])
+ Long.parseLong(toks[6]) + Long.parseLong(toks[7]) + Long.parseLong(toks[8]);
return (float)(cpu2 - cpu1) / ((cpu2 + idle2) - (cpu1 + idle1));
} catch (IOException ex) {
ex.printStackTrace();
}
return 0;
}
private List<MockData> loadDataFileHead(RandomAccessFile rf) throws IOException {
List<MockData> mockDataList = new ArrayList<>();
long fileLength = rf.length();
// 返回此文件中的当前偏移量
long start = rf.getFilePointer();
long readIndex = start + fileLength -1;
String line;
// 设置偏移量为文件末尾
rf.seek(readIndex);
int c = -1;
while (readIndex > start) {
c = rf.read();
String readText = null;
if (c == '\n' || c == '\r') {
line = rf.readLine();
if (line != null) {
readText = new String(line.getBytes("ISO-8859-1"));
}
if(StringUtils.isBlank(readText)){
continue;
}
if(Constants.RESPONSE_DATA_DELIMITER.equals(readText)){
break;
}else{
MockData mockData = createMockDataHead(readText);
mockDataList.add(mockData);
}
readIndex--;
}
readIndex--;
rf.seek(readIndex);
}
return mockDataList;
}
private String readLine(RandomAccessFile raf) throws IOException {
String line = raf.readLine();
if(StringUtils.isBlank(line)){
return line;
}
line = new String(line.getBytes("ISO-8859-1"), "utf-8");
line = StringUtils.trim(line);
return line;
}
public static double getCpuUsage0() {
try {
RandomAccessFile reader = new RandomAccessFile("/proc/stat", "r");
String load = reader.readLine();
String[] toks = load.split(" ");
double idle1 = Double.parseDouble(toks[5]);
double cpu1 = Double.parseDouble(toks[2])
+ Double.parseDouble(toks[3]) + Double.parseDouble(toks[4])
+ Double.parseDouble(toks[6]) + Double.parseDouble(toks[8])
+ Double.parseDouble(toks[7]);
// 2:user 3:nice 4:system 6:iowait 7:irq 8:softirq
try {
Thread.sleep(360);
} catch (Exception e) {
e.printStackTrace();
}
reader.seek(0);
load = reader.readLine();
reader.close();
toks = load.split(" ");
double idle2 = Double.parseDouble(toks[5]);
double cpu2 = Double.parseDouble(toks[2])
+ Double.parseDouble(toks[3]) + Double.parseDouble(toks[4])
+ Double.parseDouble(toks[6]) + Double.parseDouble(toks[8])
+ Double.parseDouble(toks[7]);
double value = div((100.00 * ((cpu2 - cpu1))),
(cpu2 + idle2) - (cpu1 + idle1), 2);
// BigDecimal b = new BigDecimal(Double.toString(value));
// double res = b.setScale(2,
// BigDecimal.ROUND_HALF_UP).doubleValue();
return value;
} catch (IOException ex) {
ex.printStackTrace();
}
return 0;
}
@TargetApi(Build.VERSION_CODES.JELLY_BEAN)
private long getSizeTotalRAM(boolean isTotal) {
long sizeInBytes = 1000;
MemoryInfo mi = new MemoryInfo();
activityManager.getMemoryInfo(mi);
if(isTotal) {
try {
if(Utils.hasJellyBean()){
long totalMegs = mi.totalMem;
sizeInBytes = totalMegs;
}
else{
RandomAccessFile reader = new RandomAccessFile("/proc/meminfo", "r");
String load = reader.readLine();
String[] totrm = load.split(" kB");
String[] trm = totrm[0].split(" ");
sizeInBytes=Long.parseLong(trm[trm.length-1]);
sizeInBytes=sizeInBytes*1024;
reader.close();
}
}
catch (Exception e) { }
}
else{
long availableMegs = mi.availMem;
sizeInBytes = availableMegs;
}
return sizeInBytes;
}
private String readFirstLineOfFile(String fn) {
String lineData = "";
try{
RandomAccessFile inFile = new RandomAccessFile(fn, "r");
lineData = inFile.readLine();
inFile.close();
}
// file not found
catch(Exception e){
// Log.i("IntrospyLog", "--> "+ e);
// app won't be hooked
}
return lineData;
}
public static void main(String[] args) {
try {
RandomAccessFile file = new RandomAccessFile("/Users/pankaj/Downloads/myfile.txt", "r");
String str;
while ((str = file.readLine()) != null) {
System.out.println(str);
}
file.close();
} catch (IOException e) {
e.printStackTrace();
}
}
private long findNextEOLPosition(RandomAccessFile seeakable, long blocksize)
throws IOException, EndReachedException {
if (seeakable.skipBytes((int) blocksize) < blocksize)
throw new EndReachedException();
else
seeakable.readLine();
return seeakable.getFilePointer();
}
public static DxfGroup readGroup( RandomAccessFile raf ) throws IOException {
try {
long pos = raf.getFilePointer();
String line1 = raf.readLine();
String line2 = raf.readLine();
DxfGroup dxfGroup = new DxfGroup(Integer.parseInt(line1.trim()), line2);
dxfGroup.setAddress(pos);
return dxfGroup;
} catch (IOException ioe) {
raf.close();
throw ioe;
}
}
/**
* Modifies the dagman condor submit file for metrics reporting.
*
* @param file
* @return true if file is modified, else false
* @throws CodeGeneratorException
*/
protected boolean modifyDAGManSubmitFileForMetrics(File file) throws CodeGeneratorException {
// modify the environment string to add the environment for
// enabling DAGMan metrics if so required.
Metrics metricsReporter = new Metrics();
metricsReporter.initialize(mBag);
ENV env = metricsReporter.getDAGManMetricsEnv();
if (env.isEmpty()) {
return false;
} else {
// we read the DAGMan submit file in and grab the environment from it
// and add the environment key to the second last line with the
// Pegasus metrics environment variables added.
try {
RandomAccessFile raf = new RandomAccessFile(file, "rw");
String dagmanEnvString = "";
String line = null;
long previous = raf.getFilePointer();
while ((line = raf.readLine()) != null) {
if (line.startsWith("environment")) {
dagmanEnvString = line;
}
if (line.startsWith("queue")) {
// backtrack to previous file position i.e just before queue
raf.seek(previous);
StringBuilder dagmanEnv = new StringBuilder(dagmanEnvString);
if (dagmanEnvString.isEmpty()) {
dagmanEnv.append("environment=");
} else {
dagmanEnv.append(";");
}
for (Iterator it = env.getProfileKeyIterator(); it.hasNext(); ) {
String key = (String) it.next();
dagmanEnv.append(key).append("=").append(env.get(key)).append(";");
}
mLogger.log(
"Updated environment for dagman is " + dagmanEnv.toString(),
LogManager.DEBUG_MESSAGE_LEVEL);
raf.writeBytes(dagmanEnv.toString());
raf.writeBytes(System.getProperty("line.separator", "\r\n"));
raf.writeBytes("queue");
break;
}
previous = raf.getFilePointer();
}
raf.close();
} catch (IOException e) {
throw new CodeGeneratorException(
"Error while reading dagman .condor.sub file " + file, e);
}
}
return true;
}
/**
* Attempts to acquire an exclusive lock on the storage.
*
* @return A lock object representing the newly-acquired lock or
* <code>null</code> if storage is already locked.
* @throws IOException if locking fails.
*/
@SuppressWarnings("resource")
FileLock tryLock() throws IOException {
boolean deletionHookAdded = false;
File lockF = new File(root, STORAGE_FILE_LOCK);
if (!lockF.exists()) {
lockF.deleteOnExit();
deletionHookAdded = true;
}
RandomAccessFile file = new RandomAccessFile(lockF, "rws");
String jvmName = ManagementFactory.getRuntimeMXBean().getName();
FileLock res = null;
try {
res = file.getChannel().tryLock();
if (null == res) {
throw new OverlappingFileLockException();
}
file.write(jvmName.getBytes(Charsets.UTF_8));
LOG.info("Lock on " + lockF + " acquired by nodename " + jvmName);
} catch(OverlappingFileLockException oe) {
// Cannot read from the locked file on Windows.
String lockingJvmName = Path.WINDOWS ? "" : (" " + file.readLine());
LOG.error("It appears that another node " + lockingJvmName
+ " has already locked the storage directory: " + root, oe);
file.close();
return null;
} catch(IOException e) {
LOG.error("Failed to acquire lock on " + lockF
+ ". If this storage directory is mounted via NFS, "
+ "ensure that the appropriate nfs lock services are running.", e);
file.close();
throw e;
}
if (!deletionHookAdded) {
// If the file existed prior to our startup, we didn't
// call deleteOnExit above. But since we successfully locked
// the dir, we can take care of cleaning it up.
lockF.deleteOnExit();
}
return res;
}
/**
* Attempts to acquire an exclusive lock on the storage.
*
* @return A lock object representing the newly-acquired lock or
* <code>null</code> if storage is already locked.
* @throws IOException if locking fails.
*/
@SuppressWarnings("resource")
FileLock tryLock() throws IOException {
boolean deletionHookAdded = false;
File lockF = new File(root, STORAGE_FILE_LOCK);
if (!lockF.exists()) {
lockF.deleteOnExit();
deletionHookAdded = true;
}
RandomAccessFile file = new RandomAccessFile(lockF, "rws");
String jvmName = ManagementFactory.getRuntimeMXBean().getName();
FileLock res = null;
try {
res = file.getChannel().tryLock();
if (null == res) {
throw new OverlappingFileLockException();
}
file.write(jvmName.getBytes(Charsets.UTF_8));
LOG.info("Lock on " + lockF + " acquired by nodename " + jvmName);
} catch(OverlappingFileLockException oe) {
// Cannot read from the locked file on Windows.
String lockingJvmName = Path.WINDOWS ? "" : (" " + file.readLine());
LOG.error("It appears that another node " + lockingJvmName
+ " has already locked the storage directory: " + root, oe);
file.close();
return null;
} catch(IOException e) {
LOG.error("Failed to acquire lock on " + lockF
+ ". If this storage directory is mounted via NFS, "
+ "ensure that the appropriate nfs lock services are running.", e);
file.close();
throw e;
}
if (!deletionHookAdded) {
// If the file existed prior to our startup, we didn't
// call deleteOnExit above. But since we successfully locked
// the dir, we can take care of cleaning it up.
lockF.deleteOnExit();
}
return res;
}
/**
* @throws Exception If failed.
*/
@Test
public void testReadLineFromBinaryFile() throws Exception {
File file = new File(FILE_PATH);
file.deleteOnExit();
RandomAccessFile raf = new RandomAccessFile(file, "rw");
byte[] b = new byte[100];
Arrays.fill(b, (byte)10);
raf.write(b);
raf.writeBytes("swap-spaces/space1/b53b3a3d6ab90ce0268229151c9bde11|" +
"b53b3a3d6ab90ce0268229151c9bde11|1315392441288" + U.nl());
raf.writeBytes("swap-spaces/space1/b53b3a3d6ab90ce0268229151c9bde11|" +
"b53b3a3d6ab90ce0268229151c9bde11|1315392441288" + U.nl());
raf.write(b);
raf.writeBytes("test" + U.nl());
raf.getFD().sync();
raf.seek(0);
while (raf.getFilePointer() < raf.length()) {
String s = raf.readLine();
X.println("String: " + s + ";");
X.println("String length: " + s.length());
X.println("File pointer: " + raf.getFilePointer());
}
}