【原创】Java实现内存共享
内存共享就是对同一段内存的读写;用来进行进程之间的通信。
首先是写的代码：
package com.sharememory.test;import java.io.IOException;import java.io.RandomAccessFile;import java.nio.MappedByteBuffer;import java.nio.channels.FileChannel;import java.nio.channels.FileLock;public class WriteMemory {String fileName = "shm.lock";RandomAccessFile raFile;FileChannel fc;int iSize = 1024;MappedByteBuffer mapBuf;int iMode;public WriteMemory() {try {init();} catch (Exception e) {e.printStackTrace();}}public void init() throws Exception {raFile = new RandomAccessFile(fileName, "rw");fc = raFile.getChannel();mapBuf = fc.map(FileChannel.MapMode.READ_WRITE, 0, iSize);}public void clearBuffer() {// 清除文件内容for (int i = 0; i < 1024; i++) {mapBuf.put(i, (byte) 0);}}public void putBuffer() throws Exception{for (int i = 65; i < 91; i++) {int index = i - 63;int flag = mapBuf.get(0); // 可读标置第一个字节为 0if (flag != 0) { // 不是可写标示 0，则重复循环，等待i--;continue;}mapBuf.put(0, (byte) 1); // 正在写数据，标志第一个字节为 1mapBuf.put(1, (byte) (index)); // 写数据的位置System.out.println("程序 WriteShareMemory："+ System.currentTimeMillis() + "：位置：" + index + " 写入数据："+ (char) i);mapBuf.put(index, (byte) i);// index 位置写入数据mapBuf.put(0, (byte) 2); // 置可读数据标志第一个字节为 2Thread.sleep(513);}}public boolean getLock() {FileLock lock = null;try {lock = fc.tryLock();} catch (IOException e) {e.printStackTrace();}if (lock == null) {return false;} else {return true;}}public static void main(String[] args) {// TODO Auto-generated method stubWriteMemory map = new WriteMemory();if (map.getLock()) {try {map.putBuffer();} catch (Exception e) {e.printStackTrace();}} else {System.out.println("can't get lock");}}}package com.sharememory.test;import java.io.IOException;import java.io.RandomAccessFile;import java.nio.MappedByteBuffer;import java.nio.channels.FileChannel;import java.nio.channels.FileLock;public class ReadMemory {String fileName = "shm.lock";RandomAccessFile raFile;FileChannel fc;int iSize = 1024;MappedByteBuffer mapBuf;int iMode;int lastIndex = 0;public ReadMemory() {try {init();} catch (Exception e) {e.printStackTrace();}}public void init() throws Exception {raFile = new RandomAccessFile(fileName, "rw");fc = raFile.getChannel();mapBuf = fc.map(FileChannel.MapMode.READ_WRITE, 0, iSize);}public void clearBuffer() {// 清除文件内容for (int i = 0; i < 1024; i++) {mapBuf.put(i, (byte) 0);}}public void getBuffer() throws Exception{ for(int i=1;i<27;i++){ int flag = mapBuf.get(0); //取读写数据的标志 int index = mapBuf.get(1); //读取数据的位置,2 为可读 if(flag != 2 || index == lastIndex){ //假如不可读，或未写入新数据时重复循环 i--; continue; } lastIndex = index; System.out.println("程序 ReadShareMemory：" + System.currentTimeMillis() + "：位置：" + index +" 读出数据：" + (char)mapBuf.get(index)); mapBuf.put(0,(byte)0); //置第一个字节为可读标志为 0 if(index == 27){ //读完数据后退出 break; } }}public boolean getLock() {FileLock lock = null;try {lock = fc.tryLock();} catch (IOException e) {e.printStackTrace();}if (lock == null) {return false;} else {return true;}}public static void main(String[] args) {// TODO Auto-generated method stubReadMemory map = new ReadMemory();if (map.getLock()) {try {map.getBuffer();} catch (Exception e) {e.printStackTrace();}} else {System.out.println("can't get lock");}}}