近期在实现项目接口时，经常需要分页功能。有时返回“String”,有时是“Object”格式的分页List。针对这种情况，本人用java实现对List分页。
第一版
代码语言：javascript复制package org.sun.java;
import java.util.ArrayList;
import java.util.List;
/**
*
* @author Administrator
* @date 2016年7月16日
*/
public class SubListOperation {
final static int COUNT = 18;
public List<String> init(int size) {
List<String> lists = new ArrayList<String>();
for (int i = 0; i < size; i ) {
lists.add("t" (i 1));
}
return lists;
}
/**
*
* @param pageNum
* @param pageSize
* @return 简单分页功能
*/
public List<String> subList(int pageNum, int pageSize) {
List<String> lists = init(COUNT);
int fromIndex = (pageNum - 1) * pageSize;
int toIndex = fromIndex pageSize;
return lists.subList(fromIndex, toIndex);
}
public static void main(String[] args) {
System.out.println("-------- start --------");
new SubListOperation().output();
System.out.println("-------- finish --------");
}
public void output(){
int pageNum=2;
int pageSize=5;
for(String s:subList(pageNum,pageSize)){
System.out.println(s);
}
}
}-------- start -------- t6 t7 t8 t9 t10 -------- finish --------
考虑到超出元素个数时异常的情况，做多一步判断。
第二版
代码语言：javascript复制
/**
*
* @param pageNum
* @param pageSize
* @return 简单分页功能
*/
public List<String> subList(int pageNum, int pageSize) {
List<String> lists = init(COUNT);
int fromIndex = (pageNum - 1) * pageSize;
int toIndex = fromIndex pageSize;
int size = lists.size();
if(fromIndex>=size){
return new ArrayList<String>();
}
return lists.subList(fromIndex, Math.min(size,toIndex));
}第三版
代码语言：javascript复制package org.sun.java;
import java.util.ArrayList;
import java.util.List;
/**
*
* @author Administrator
* @date 2016年7月16日
*/
public class SubListOperation {
final static int COUNT = 18;
public List<String> init(int size) {
List<String> lists = new ArrayList<String>();
for (int i = 0; i < size; i ) {
lists.add("t" (i 1));
}
return lists;
}
/**
*
* @param size
* @return 初始化用户列表
*/
public List<User> initUser(int size) {
List<User> lists = new ArrayList<User>();
for (int i = 0; i < size; i ) {
lists.add(new User((i 1), "user" (i 1)));
}
return lists;
}
/**
*
* @param pageNum
* @param pageSize
* @return 简单分页功能
*/
public List<User> userSubList(int pageNum, int pageSize) {
List<User> lists = initUser(COUNT);
int fromIndex = (pageNum - 1) * pageSize;
int toIndex = fromIndex pageSize;
int size = lists.size();
if (fromIndex >= size) {
return new ArrayList<User>();
}
return lists.subList(fromIndex, Math.min(size, toIndex));
}
public List<String> subList(int pageNum, int pageSize) {
List<String> lists = init(COUNT);
int fromIndex = (pageNum - 1) * pageSize;
int toIndex = fromIndex pageSize;
int size = lists.size();
if (fromIndex >= size) {
return new ArrayList<String>();
}
return lists.subList(fromIndex, Math.min(size, toIndex));
}
static class User {
int id;
String name;
public User(int id, String name) {
super();
this.id = id;
this.name = name;
}
@Override
public String toString() {
return "User [id=" id ", name=" name "]";
}
}
public static void main(String[] args) {
System.out.println("-------- start --------");
// new SubListOperation().outputString();
new SubListOperation().outputObject();
System.out.println("-------- finish --------");
}
public void outputString() {
int pageNum = 2;
int pageSize = 5;
for (String s : subList(pageNum, pageSize)) {
System.out.println(s);
}
}
public void outputObject() {
int pageNum = 2;
int pageSize = 5;
for (User s : userSubList(pageNum, pageSize)) {
System.out.println(s);
}
}
}-------- start --------
User [id=6, name=user6]
User [id=7, name=user7]
User [id=8, name=user8]
User [id=9, name=user9]
User [id=10, name=user10]
-------- finish --------泛型方法，通用类型实现分页
代码语言：javascript复制package org.sun.java;
import java.util.ArrayList;
import java.util.List;
/**
*
* @author Administrator
* @date 2016年7月16日
*/
public class SubListOperation {
final static int COUNT = 18;
public List<String> init(int size) {
List<String> lists = new ArrayList<String>();
for (int i = 0; i < size; i ) {
lists.add("t" (i 1));
}
return lists;
}
/**
*
* @param size
* @return 初始化用户列表
*/
public List<User> initUser(int size) {
List<User> lists = new ArrayList<User>();
for (int i = 0; i < size; i ) {
lists.add(new User((i 1), "user" (i 1)));
}
return lists;
}
/**
*
* @param lists 将被分页展示的列表
* @param pageNum 页码数
* @param pageSize 每页条数大小
* @return
*/
public <T> List<T> generalPagenation(List<T> lists,int pageNum, int pageSize) {
int fromIndex = (pageNum - 1) * pageSize;
int toIndex = fromIndex pageSize;
int size = lists.size();
if (fromIndex >= size) {
return new ArrayList<T>();
}
return lists.subList(fromIndex, Math.min(size, toIndex));
}
static class User {
int id;
String name;
public User(int id, String name) {
super();
this.id = id;
this.name = name;
}
@Override
public String toString() {
return "User [id=" id ", name=" name "]";
}
}
public static void main(String[] args) {
System.out.println("-------- start --------");
new SubListOperation().outputT();
System.out.println("-------- finish --------");
}
public void outputT() {
int pageNum = 3;
int pageSize = 5;
for (Object s : generalPagenation(init(18),pageNum, pageSize)) {
System.out.println(s);
}
System.out.println("---------***---------");
for (Object s : generalPagenation(initUser(12),pageNum, pageSize)) {
System.out.println(s);
}
}
}-------- start --------
t11
t12
t13
t14
t15
---------***---------
User [id=11, name=user11]
User [id=12, name=user12]
-------- finish --------
