相关文章
【合集】Java设计模式
应用
{@link jakarta.servlet.FilterChain}抽象处理器
职责链模式
请假流程系统：1天小组长审批通过即可，23天小组长+部门经理审批通过，37小组长+部门经理+总经理审批通过
请假条类
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@Getter
@AllArgsConstructor
public static class LeaveRequest {
private String name;
private int num;
private String content;
}
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抽象处理者
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@Setter
public static abstract class Handler {
protected final static int NUMBER_ONE = 1;
protected final static int NUMBER_THREE = 3;
protected final static int NUMBER_SEVEN = 7;
private final int numStart;
private final int numEnd;
private Handler nextHandler;
public Handler(int numStart, int numEnd) {
this.numStart = numStart;
this.numEnd = numEnd;
}
public final void submit(LeaveRequest leave) {
if (leave.getNum() == 0) return;
if (leave.getNum() >= this.numStart) {
this.handleLeave(leave);
if (leave.getNum() > numEnd && this.nextHandler != null) {
this.nextHandler.submit(leave);
} else {
System.out.println("流程结束");
}
}
}
protected abstract void handleLeave(LeaveRequest leave);
}
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具体处理者
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public static class GroupLeader extends Handler {
public GroupLeader() {
super(0, NUMBER_ONE);
}
protected void handleLeave(LeaveRequest leave) {
System.out.println("小组长审批：同意");
}
}
public static class Manager extends Handler {
public Manager() {
super(NUMBER_ONE, NUMBER_THREE);
}
protected void handleLeave(LeaveRequest leave) {
System.out.println("部门经理审批：同意");
}
}
public static class GeneralManager extends Handler {
public GeneralManager() {
super(NUMBER_THREE, NUMBER_SEVEN);
}
protected void handleLeave(LeaveRequest leave) {
System.out.println("总经理审批：同意");
}
}
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客户端调用
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LeaveRequest leave = new LeaveRequest("小花", 5, "身体不适");
System.out.println(leave.getName() + "请假" + leave.getNum() + "天，" + leave.getContent() + "。");
// 如果领导固定，可放在领导实现类中。
GeneralManager generalManager = new GeneralManager();
Manager manager = new Manager();
manager.setNextHandler(generalManager);
GroupLeader groupLeader = new GroupLeader();
groupLeader.setNextHandler(manager);
// 提交给小组长
groupLeader.submit(leave);
System.out.println("-----------------------------------------------");
// 提交给部门经理
manager.submit(leave);
System.out.println("-----------------------------------------------");
// 提交给总经理
generalManager.submit(leave);
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输出
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小花请假5天，身体不适。
小组长审批：同意
部门经理审批：同意
总经理审批：同意
流程结束
-----------------------------------------------
部门经理审批：同意
总经理审批：同意
流程结束
-----------------------------------------------
总经理审批：同意
流程结束
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模拟FilterChain
模拟Request、Response
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public interface Request {
}
public interface Response {
}
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模拟FilterChain
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public interface Filter {
void doFilter(Request req, Response res, FilterChain c);
}
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模拟实现具体过滤器
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public static class FirstFilter implements Filter {
@Override
public void doFilter(Request request, Response response, FilterChain chain) {
System.out.println("过滤器1 前置处理");
// 先执行所有request再倒序执行所有response
chain.doFilter(request, response);
System.out.println("过滤器1 后置处理");
}
}
public static class SecondFilter implements Filter {
@Override
public void doFilter(Request request, Response response, FilterChain chain) {
System.out.println("过滤器2 前置处理");
// 先执行所有request再倒序执行所有response
chain.doFilter(request, response);
System.out.println("过滤器2 后置处理");
}
}
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模拟实现过滤器链 FilterChain
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public static class FilterChain {
private final List<Filter> filters = new ArrayList<>();
private int index = 0;
public FilterChain addFilter(Filter filter) {
filters.add(filter);
return this;
}
public void doFilter(Request request, Response response) {
if (index == filters.size()) {
return;
}
Filter filter = filters.get(index);
index++;
filter.doFilter(request, response, this);
}
}
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客户端调用
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Request request = null;
Response response = null;
FilterChain filterChain = new FilterChain()
.addFilter(new FirstFilter())
.addFilter(new SecondFilter());
filterChain.doFilter(request, response);
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