Java分页、Json工具类

 1.JSON数据转换工具类

import java.util.List;
import java.util.Map;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.reflect.TypeToken;

/**
 * JSON数据互转工具类
 */
public class JsonUtils {
    
    static Gson gson = new  GsonBuilder().setDateFormat("yyyy-MM-dd HH:mm:ss").create();
    
    /** 将list转化为json字符串
     */
    public static String list2json(List<?> list) {
        if(list==null) return "[]";
        String str = gson.toJson(list);
        return str;
    }
    
    /** 将对象转化为json字符串(类 或者 Map)
     */
    public static String obj2json(Object obj) {
        if(obj==null) return "{}";
        String str = gson.toJson(obj);
        return str;
    }

    /** 将json字符串转化为List<String>
     */
    public static List<String> json2list(String jsonStr) {
        try{
            List<String> list = gson.fromJson(jsonStr, new TypeToken<List<String>>() {
            }.getType());
            return list;
        }catch(Exception e){
            //e.printStackTrace();
        }
        return null;
    }
    
    /** 将json字符串转化为List<Integer>
     */
    public static List<Integer> json2listInt(String jsonStr) {
        try{
            List<Integer> list = gson.fromJson(jsonStr, new TypeToken<List<Integer>>() {
            }.getType());
            return list;
        }catch(Exception e){
            //e.printStackTrace();
        }
        return null;
    }
    
    /** 将json字符串转化为List<Map<Object,Object>>
     */
    public static List<Map<Object,Object>> json2listMap(String jsonStr) {
        try{
            List<Map<Object,Object>> list = gson.fromJson(jsonStr, new TypeToken<List<Map<Object,Object>>>() {
            }.getType());
            return list;
        }catch(Exception e){
            e.printStackTrace();
        }
        return null;
    }
    /** 将json字符串转化为List<Map<String,Object>>
     */
    public static List<Map<String,Object>> json2listMapStrObj(String jsonStr) {
        try{
            List<Map<String,Object>> list = gson.fromJson(jsonStr, new TypeToken<List<Map<String,Object>>>() {
            }.getType());
            return list;
        }catch(Exception e){
            e.printStackTrace();
        }
        return null;
    }
    /** 将json字符串转化为List<Map<String,String>>
     */
    public static List<Map<String,String>> json2listMapStr(String jsonStr) {
        try{
            List<Map<String,String>> list = gson.fromJson(jsonStr, new TypeToken<List<Map<String,String>>>() {
            }.getType());
            return list;
        }catch(Exception e){
            e.printStackTrace();
        }
        return null;
    }
    /** 将json字符串转化为List<Object>
     */
    public static List<Object> json2listObj(String jsonStr) {
        try{
            List<Object> list = gson.fromJson(jsonStr, new TypeToken<List<Object>>() {
            }.getType());
            return list;
        }catch(Exception e){
            //e.printStackTrace();
        }
        return null;
    }
    
    /** 将json字符串转化为List<List<String>
     */
    public static List<List<String>> json2list2String(String jsonStr) {
        try{
            List<List<String>> list = gson.fromJson(jsonStr, new TypeToken<List<List<String>>>() {
            }.getType());
            return list;
        }catch(Exception e){
            //e.printStackTrace();
        }
        return null;
    }
    
    /** 将json字符串转化为Map<String,Object>
     */
    public static Map<String,Object> json2Map(String jsonStr) {
        try{
            Map<String,Object> map = gson.fromJson(jsonStr, new TypeToken<Map<String,Object>>() {
            }.getType());
            return map;
        }catch(Exception e){
            //e.printStackTrace();
        }
        return null;
    }
    
    /** 将json字符串转化为Map<String,String>
     */
    public static Map<String,String> json2MapSingleStr(String jsonStr) {
        try{
            Map<String,String> map = gson.fromJson(jsonStr, new TypeToken<Map<String,String>>() {
            }.getType());
            return map;
        }catch(Exception e){
            //e.printStackTrace();
        }
        return null;
    }
    
    /** 将json字符串转化为Map<String,Double>
     */
    public static Map<String,Double> json2MapSingleDou(String jsonStr) {
        try{
            Map<String,Double> map = gson.fromJson(jsonStr, new TypeToken<Map<String,Double>>() {
            }.getType());
            return map;
        }catch(Exception e){
            //e.printStackTrace();
        }
        return null;
    }
    
    /** 将json字符串转化为Map<String,Map<String,String>>
     */
    public static Map<String,Map<String,String>> json2MapInMapStr(String jsonStr) {
        try{
            Map<String,Map<String,String>> map = gson.fromJson(jsonStr, new TypeToken<Map<String,Map<String,String>>>() {
            }.getType());
            return map;
        }catch(Exception e){
            //e.printStackTrace();
        }
        return null;
    }

    /** 将json字符串转化为Map<String,Map<String,Float>>
     */
    public static Map<String,Map<String,Float>> json2MapInMapFloat(String jsonStr) {
        try{
            Map<String,Map<String,Float>> map = gson.fromJson(jsonStr, new TypeToken<Map<String,Map<String,Float>>>() {
            }.getType());
            return map;
        }catch(Exception e){
            //e.printStackTrace();
        }
        return null;
    }
    /** 将json字符串转化为Map<String,List<Integer>
     */
    public static Map<String,List<Integer>> json2MapInListInt(String jsonStr) {
        try{
            Map<String,List<Integer>> map = gson.fromJson(jsonStr, new TypeToken<Map<String,List<Integer>>>() {
            }.getType());
            return map;
        }catch(Exception e){
            //e.printStackTrace();
        }
        return null;
    }
    /** 将json字符串转化为Map<String,List<String>
     */
    public static Map<String,List<String>> json2MapInListString(String jsonStr) {
        try{
            Map<String,List<String>> map = gson.fromJson(jsonStr, new TypeToken<Map<String,List<String>>>() {
            }.getType());
            return map;
        }catch(Exception e){
            //e.printStackTrace();
        }
        return null;
    }
    /** 将json字符串转化为Map<String,List<List<String>>
     */
    public static Map<String,List<List<String>>> json2MapInListStringListString(String jsonStr) {
        try{
            Map<String,List<List<String>>> map = gson.fromJson(jsonStr, new TypeToken<Map<String,List<List<String>>>>() {
            }.getType());
            return map;
        }catch(Exception e){
            //e.printStackTrace();
        }
        return null;
    }
    /** 将json字符串转化为Map<String,List<Integer>
     */
    public static Map<Integer,List<Integer>> json2MapInListInt_int(String jsonStr) {
        try{
            Map<Integer,List<Integer>> map = gson.fromJson(jsonStr, new TypeToken<Map<Integer,List<Integer>>>() {
            }.getType());
            return map;
        }catch(Exception e){
            //e.printStackTrace();
        }
        return null;
    }
    /** 将json字符串转化为List<String[]>
     */
    public static List<String[]> json2ListStrArr(String jsonStr) {
        try{
            List<String[]> list = gson.fromJson(jsonStr, new TypeToken<List<String[]>>() {
            }.getType());
            return list;
        }catch(Exception e){
            //e.printStackTrace();
        }
        return null;
    }
    
    /** 将json字符串转化为List<Float[]>
     */
    public static List<Float[]> json2ListFloatArr(String jsonStr) {
        try{
            List<Float[]> list = gson.fromJson(jsonStr, new TypeToken<List<Float[]>>() {
            }.getType());
            return list;
        }catch(Exception e){
            //e.printStackTrace();
        }
        return null;
    }
    
    /** 将json字符串转化为List<Float>
     */
    public static List<Float> json2ListFloat(String jsonStr) {
        try{
            List<Float> list = gson.fromJson(jsonStr, new TypeToken<List<Float>>() {
            }.getType());
            return list;
        }catch(Exception e){
            //e.printStackTrace();
        }
        return null;
    }
    
    /** 将json字符串转化为AjaxDto
     */
    /*public static AjaxDto json2AjaxDto(String jsonStr) {
        AjaxDto map = gson.fromJson(jsonStr, new TypeToken<AjaxDto>() {
        }.getType());
        return map;
    }*/
    
    
}

　　注：需要引入cosn.jar包。

2.分页工具类

/**分页工具类
 */
public class Pager<T> {
    
    /** 换数据类型时使用
     */
    public Pager(Pager<?> pager,List<?> datas){
        this.currPage=pager.currPage;
        this.pages=pager.pages;
        this.pageSize=pager.pageSize;
        this.count=pager.count;
        this.ind=pager.ind;
        this.datas=(List<T>)datas;
    }

    public Pager(int currPage){
        this.currPage=currPage<1?1:currPage;
    }
    public Pager(int currPage,int pageSize){
        this.currPage=currPage<1?1:currPage;
        this.pageSize=pageSize;
    }
    
    
    private int currPage;//当前页     设置-100时，则不分页和获取页数(只在有需要的地方加此逻辑)
    private int pages;//总页数
    private int pageSize=10;//每页条数
    private int count;//总条数
    private int ind;
    private List<T> datas;
    private Object other;
    
    
    public Pager<T> setData(int count,List<T> datas){
        this.setCount(count);
        this.datas=datas;
        return this;
    }
    /** 不能确认每页条数才使用
     */ 
    public Pager<T> setDataLikeCount(int pages,List<T> datas){
        this.pages=pages;
        this.datas=datas;
        return this;
    }
    public List<T> getData(){
        return this.datas;
    }
    
    private void setCount(int count) {
        this.count = count;
        this.ind = ((currPage-1)*pageSize)+1;
        this.pages = count==0?1:((int)(count/pageSize+(count%pageSize==0?0:1)));
    }
    public int getCount(){
        return count;
    }
    /** 获取每页条数
     */
    public int getPageSize(){
        return this.pageSize;
    }
    
    public int getStartCount(){
        return (currPage - 1) * pageSize;
    }
    public Object getOther() {
        return other;
    }
    public void setOther(Object other) {
        this.other = other;
    }
    public String toJson(){
        return JsonUtils.obj2json(this);
    }
    public static Pager<Object> getBlankDatas(){
        Pager<Object> pager = new Pager<Object>(1);
        pager.setData(0,new ArrayList<Object>(0));
        return pager;
    }
}

 　　注：该类中引用了JSON数据转换工具类，可以改成自己需要的，也可以删除。

3.接口返回工具类

public class AjaxDto {
    
    public AjaxDto(){}
    
    public AjaxDto(int result){
        this.result=result;
    }
    
    public AjaxDto(int result, String msg, Object obj) {
        this.result = result;
        this.msg = msg;
        this.obj = obj;
    }

    public AjaxDto(int result, String msg) {
        this.result = result;
        this.msg = msg;
    }
    
    public AjaxDto(int result, String msg,HttpServletRequest request) {
        this.result = result;
        this.msg = msg;
        this.request=request;
    }
    
    public AjaxDto(int result, String msg, Object obj,HttpServletRequest request) {
        this.result = result;
        this.msg = msg;
        this.obj = obj;
        this.request=request;
    }

    /**
     * 0表示失败 1表示成功
     */
    private int result;
    /**
     * 提示信息
     */
    private String msg;
    /**
     * 附加对象，用来存储一些特定的返回信息
     */
    protected Object obj;
    
    private transient HttpServletRequest request;

    public int getResult() {
        return result;
    }

    public void setResult(int result) {
        this.result = result;
    }
    
    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }
    public Object getObj() {
        return obj;
    }
    public void setObj(Object obj) {
        this.obj = obj;
    }
    public  HttpServletRequest getRequest() {
        return request;
    }

    public void setRequest(HttpServletRequest request) {
        this.request = request;
    }

    
    public String toJson(){
        if(request==null)
            return JsonUtils.obj2json(this);
        else
            return toJson(request);
    }
    public String toJson(HttpServletRequest request){
        return JsonUtils.obj2json(this);
    }
}

　　注：该类中引用了JSON数据转换工具类，可以改成自己需要的，也可以删除。