Java实现简单的模板渲染

package com.hdwang;

import java.util.HashMap;
import java.util.Map;

/**
 * Created by hdwang on 2017/12/19.
 */
public class MyTemplate {

 public static void main(String[] args){

  String template = "${name},${sex},${birthYear}年出生,${graduateYear}年毕业于${university}。";
  Map<String,String> params = new HashMap<>();
  params.put("name","张三");
  params.put("sex","男");
  params.put("birthYear","1990");
  params.put("graduateYear","2012");
  params.put("university","清华大学");

  long start = System.currentTimeMillis();

  for(int i=0;i<10000;i++) {
   String result = render(template, params);

   if(i==9999) {
    System.out.println(result);
   }
  }
  long end = System.currentTimeMillis();


  System.out.println("cost time:"+(end-start)+"ms");

  start = System.currentTimeMillis();
  for(int i=0;i<10000;i++) {
   String result = render2(template, params);

   if(i==9999) {
    System.out.println(result);
   }
  }
  end = System.currentTimeMillis();
  System.out.println("cost time:"+(end-start)+"ms");

 }

 public static String render(String template,Map<String,String> params){
  //使用builder拼接，比string相加提高不少效率
  StringBuilder builder = new StringBuilder();

  //定义控制变量
  boolean $Begin = false;
  boolean paramBegin = false;
  //boolean paramEnd = false;
  StringBuilder key = null;

  //循环匹配
  for(int i=0;i<template.length();i++){
   char c = template.charAt(i);
   //开始标识
   if(c=='$'){
    $Begin = true;
   }
   if($Begin && c=='{'){
    paramBegin = true;
    builder.deleteCharAt(builder.length()-1); //删除添加的$字符

    key = new StringBuilder();
    continue;
   }

   //参数key
   if(paramBegin && c!='}'){
    if(c=='{'){
     System.out.println("模板格式错误！位置："+i);
    }else {
     key.append(c);
    }
    continue;
   }

   //结束标识
   if(paramBegin && c=='}'){
    //paramEnd = true;
    //拼接参数key对应的值
    builder.append(params.get(key.toString()));

    //重置控制变量
    $Begin = false;
    paramBegin = false;
    //paramEnd = false;
    continue;
   }

   //默认情况
   builder.append(c); //添加字符
  }

  return builder.toString();
 }

 public static String render2(String template,Map<String,String> params){
  for(Map.Entry<String,String> entry:params.entrySet()){
   String key = entry.getKey();
   String value = entry.getValue();
   template = template.replace("${"+key+"}",value);
  }
  return template;
 }
}