缓存List并写入文件持久化

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缓存list并写入文件持久化

需要缓存一个list集合，比如缓存一个输入框中用户之前输入过的内容，下次当用户再想往输入框中写东西就调用这个缓存的接口，把之前输入过的东西从缓存中取出并返回；

而为了这么一个小小的缓存，引入第三方库redis或是cache等也不太划算，于是就可以把缓存写入文件中，序列化到java虚拟机中，这样就可以支持持久化，即使重启项目缓存的list依然存在；

缓存工具类：

 1 package com.xinyan.springcloud.tjt;
 2 
 3 
 4 import java.io.file;
 5 import java.io.fileinputstream;
 6 import java.io.fileoutputstream;
 7 import java.io.ioexception;
 8 import java.io.objectinputstream;
 9 import java.io.objectoutputstream;
10 import java.io.serializable;
11 import java.util.arrays;
12 import java.util.list;
13 
14 public class streamutils implements serializable{
15     private static final long serialversionuid = 1l;
16     /**
17      * 序列化,list
18      * @param list
19      * @param file
20      * @param <t>
21      * @return
22      */
23     public static  <t> boolean writeobject(list<t> list,file file)
24     {
25         t[] array = (t[]) list.toarray();
26         try(objectoutputstream out = new objectoutputstream(new fileoutputstream(file)))
27         {
28             out.writeobject(array);
29             out.flush();
30             return true;
31         }
32         catch (ioexception e)
33         {
34             e.printstacktrace();
35             return false;
36         }
37     }
38 
39     /**
40      * 反序列化,list
41      * @param file
42      * @param <e>
43      * @return
44      */
45     public static <e> list<e> readobjectforlist(file file)
46     {
47         e[] object;
48         try(objectinputstream out = new objectinputstream(new fileinputstream(file)))
49         {
50             object = (e[]) out.readobject();
51             return arrays.aslist(object);
52         }
53         catch (ioexception e)
54         {
55             e.printstacktrace();
56         }
57         catch (classnotfoundexception e)
58         {
59             e.printstacktrace();
60         }
61         return null;
62     }
63 
64 }

测试缓存结果：

 1 package com.xinyan.springcloud.tjt;
 2 
 3 import java.io.file;
 4 import java.util.arraylist;
 5 import java.util.list;
 6 
 7 import lombok.extern.log4j.log4j;
 8 
 9 @log4j
10 public class teststreamutils {
11     
12     private final static list<string> listsave = new arraylist<>();
13     private final static string  file_cache = "file-tjt";
14     
15     public static void main(string[] args) throws exception {
16         teststreamutils.savelisttojvm("admin");
17         teststreamutils.savelisttojvm("user");
18         teststreamutils.savelisttojvm("lieiwantto");
19         object listfromjvm = teststreamutils.getlistfromjvm();
20         system.out.println("listfromjvm:"+listfromjvm);
21     }
22     
23     
24     public static void savelisttojvm(string input) throws exception{
25         list<string> listinput = new arraylist<>();
26         listsave.add(input);
27         listinput.addall(listsave);
28         boolean writeobject = streamutils.writeobject(listinput, new file(file_cache));
29         if (!writeobject) {
30             log.info("savelisttojvm failed!");
31         }
32     }
33     
34     public static object getlistfromjvm() {
35         file file = new file(file_cache);
36         list<object> readobjectforlist = null;
37         if (file.exists()) {
38              readobjectforlist = streamutils.readobjectforlist(file);
39              if (readobjectforlist.size() >20) {
40                 readobjectforlist.remove(0);
41             }
42         }else {
43             log.info("file not exist!");
44         }
45         return readobjectforlist;
46     }
47 
48 }

测试结果如下图：