package com.demo.test; import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap; /**
* @author QQ: 1236897
*
*/ //基于委托的线程安全
class Point { public final int x, y; public Point(int x, int y) {
this.x = x;
this.y = y;
} /* (non-Javadoc)
* @see java.lang.Object#toString()
*/
@Override
public String toString() {
// TODO Auto-generated method stub
return "x: "+x+", y: "+y;
} }
//返回locations后 修改point坐标,对返回map里的point->有影响
class DelegateTracker { private final ConcurrentMap<String, Point> locations;
private final Map<String, Point> unmodifiableMap; public DelegateTracker(Map<String, Point> points) { locations = new ConcurrentHashMap<String, Point>(points);
unmodifiableMap = Collections.unmodifiableMap(locations);
} public Map<String, Point> getLocations() {
return unmodifiableMap;
} public Point getLocation(String id) {
return locations.get(id);
} public void setLocation(String id, int x, int y) {
if (locations.replace(id, new Point(x, y)) == null) {
throw new IllegalArgumentException("invalid id - " + id);
}
} } //返回locations后 修改point坐标,对返回map里的point -> 没有影响
class DelegateTrackerFixedPoint { private final ConcurrentMap<String, Point> locations;
private final Map<String, Point> unmodifiableMap; public DelegateTrackerFixedPoint(Map<String, Point> points) { locations = new ConcurrentHashMap<String, Point>(points);
unmodifiableMap = Collections.unmodifiableMap(locations);
} //不同
public Map<String, Point> getLocations() {
return Collections.unmodifiableMap(new HashMap<String,Point>(locations));
} public Point getLocation(String id) {
return locations.get(id);
} public void setLocation(String id, int x, int y) {
if (locations.replace(id, new Point(x, y)) == null) {
throw new IllegalArgumentException("invalid id - " + id);
}
} } public class ThreadDemo1 { public static void main(String[] args) { //test1 - DelegateTracker
Point p1 = new Point(1,1);
Point p2 = new Point(2,2);
Point p3 = new Point(3,3);
Point p4 = new Point(4,4);
Point p5 = new Point(5,5); Map<String,Point> points = new HashMap<String,Point>(); points.put("1", p1);
points.put("2", p2);
points.put("3", p3);
points.put("4", p4);
points.put("5", p5); DelegateTracker delegateTracker = new DelegateTracker(points); delegateTracker.setLocation("2", 99, 99); Map<String,Point> result = delegateTracker.getLocations(); delegateTracker.setLocation("3", 33, 33); for(String key:result.keySet())
{
Point point = result.get(key);
System.out.println(point.toString());
}
System.out.println("-----------------------------------------"); //test2 - DelegateTrackerFixedPoint
Point f1 = new Point(1,1);
Point f2 = new Point(2,2);
Point f3 = new Point(3,3);
Point f4 = new Point(4,4);
Point f5 = new Point(5,5); Map<String,Point> points2 = new HashMap<String,Point>(); points2.put("1", f1);
points2.put("2", f2);
points2.put("3", f3);
points2.put("4", f4);
points2.put("5", f5); DelegateTrackerFixedPoint delegateTrackerFixedPoint = new DelegateTrackerFixedPoint(points2); delegateTrackerFixedPoint.setLocation("2", 99, 99); Map<String,Point> result2 = delegateTrackerFixedPoint.getLocations(); delegateTrackerFixedPoint.setLocation("3", 33, 33); for(String key:result2.keySet())
{
Point point = result2.get(key);
System.out.println(point.toString());
}
} }
package com.demo.test2; import java.util.Collections;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap; /**
* @author QQ: 1236897
*
*/
// 基于发布的线程安全 操作对象安全
class SafePoint { private int x, y; private SafePoint(int[] a) {
this(a[0], a[1]);
} public SafePoint(SafePoint p) {
this(p.get());
} public SafePoint(int x, int y) {
this.x = x;
this.y = y;
} public synchronized int[] get() {
return new int[] { x, y };
} public synchronized void set(int x, int y) {
this.x = x;
this.y = y;
} } //取出 Locations后,如果更改点位置,locations里的点会跟随变化
class PublishTracker{ private final ConcurrentMap<String, SafePoint> locations;
private final Map<String, SafePoint> unmodifiableMap; public PublishTracker(Map<String, SafePoint> points) { locations = new ConcurrentHashMap<String, SafePoint>(points);
unmodifiableMap = Collections.unmodifiableMap(locations);
} public Map<String, SafePoint> getLocations() {
return unmodifiableMap;
} public SafePoint getLocation(String id) {
return locations.get(id);
} public void setLocation(String id, int x, int y) {
if (!locations.containsKey(id)) {
throw new IllegalArgumentException("invalid id - " + id);
}
locations.get(id).set(x, y);
} } public class ThreadTest2 { /**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub } }