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RSS订阅原创 Java使用DBCP连接池
DBCP 是 apache 上的一个 java 连接池项目，也是 tomcat 使用的连接池组件。单独使用dbcp需要3个包：common-dbcp.jar,common-pool.jar,common-collections.jar。package cn.com.***;import com.google.gson.Gson;import org.apache.commons.dbcp2
2016-08-22 14:41:58
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原创 Apache Thrift - java开发教程
1.开发所需要的jar包： org.apache.thrift libthrift 0.9.0 org.slf4j slf4j-api 1.7.12 2. 安装Thrift环境
2016-07-29 15:33:55
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原创 Sort a Map<Key, Value> by values (Java) HashMap按value值排序
对HashMap按value值的大小进行排序，方法如下。import java.util.*;public class MapUtil{ public static > Map sortByValue( Map map ) { List> list = new LinkedList>( map.entrySet() )
2016-07-12 17:35:44
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原创 JAVA解析EXCEL文件
首先，需要导入POI包。 1.解析.xlsx后缀名的的EXCEL文件：package com.shuai.hello;import java.io.FileInputStream;import java.io.IOException;import java.io.InputStream;import org.apache.poi.hssf.usermodel.HS
2016-07-07 14:56:40
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原创 1
@WebServlet(name="UploadServlet",urlPatterns="/UploadServlet")@MultipartConfig//标识Servlet支持文件上传public class UploadServlet extends HttpServlet { public void doGet(HttpServletRequest request, Http
2015-11-11 22:42:55
475
原创 JAVA中的优先级队列PriorityQueue
优先级队列是不同于先进先出队列的另一种队列。每次从队列中取出的是具有最高优先权的元素。PriorityQueue是从JDK1.5开始提供的新的数据结构接口。如果不提供Comparator的话，优先队列中元素默认按自然顺序排列，也就是数字默认是小的在队列头，字符串则按字典序排列。import java.util.Comparator;import java.util.PriorityQ
2015-09-18 17:38:42
468
原创 Java多线程
线程：表示程序的执行流程，是CPU调度执行的基本单位；线程有自己的程序计数器、寄存器、堆栈和帧。同一进程中的线程共用相同的地址空间，同时共享进进程锁拥有的内存和其他资源。JAVA多线程实现方式主要有三种：继承Thread类、实现Runnable接口、使用ExecutorService、Callable、Future实现有返回结果的多线程。其中前两种方式线程执行完后都没有返回值，
2015-09-02 17:54:14
423
原创 JAVA查询Oracle数据库导出成txt文本
import java.io.FileOutputStream;import java.io.PrintStream;import java.sql.Statement;import java.sql.Connection;import java.sql.DriverManager;import java.sql.ResultSet;import java.sql.SQLExcepti
2015-08-12 15:41:37
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原创 MySQL SQL优化
前言有人反馈之前几篇文章过于理论缺少实际操作细节，这篇文章就多一些可操作性的内容吧。注：这篇文章是以 MySQL 为背景，很多内容同时适用于其他关系型数据库，需要有一些索引知识为基础。 优化目标 1.减少 IO 次数 IO永远是数据库最容易瓶颈的地方，这是由数据库的职责所决定的，大部分数据库操作中超过90%的时间都是 IO 操作所占用的，减少 I
2015-05-06 09:28:02
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原创 Leetcode:Longest Palindromic Substring
Given a string S, find the longest palindromic substring in S. You may assume that the maximum length of S is 1000, and there exists one unique longest palindromic substring.基本思路：回文字符串显然有个特征是沿
2015-04-26 14:58:02
683
原创 Leetcode:Set Matrix Zeroes
Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in place.遍历矩阵，如果遇到等于0的元素，则把该元素所在行的第一个元素和所在列第一个元素置为0。考虑到row0和col0会重合，所以另外设置一个变量col0来表示第一列的情况。然后从左下角开始，把符合条件的元素置
2015-04-23 12:28:15
602
原创 Leetcode:Palindrome Partitioning
Given a string s, partition s such that every substring of the partition is a palindrome.Return all possible palindrome partitioning of s.For example, given s = "aab",Return [ ["aa","
2015-04-08 13:43:37
527
原创 二叉树的前序，中序及后续遍历
前序遍历：先访问跟结点，然后遍历左子树，最后遍历右子树。即“根左右”。实现代码：class Solution {public: vector preorderTraversal(TreeNode *root) { if (root==NULL) { return vector(); } vector resu
2015-04-07 15:45:36
635
原创 Leetcode:Binary Search Tree Iterator
Implement an iterator over a binary search tree (BST). Your iterator will be initialized with the root node of a BST.Calling next() will return the next smallest number in the BST.Note: next()
2015-04-07 12:37:39
466
原创 二叉树的层序遍历
Given a binary tree, return the level order traversal of its nodes' values. (ie, from left to right, level by level).For example:Given binary tree {3,9,20,#,#,15,7}, 3 / \ 9 20
2015-03-31 13:23:04
660
原创 Leetcode:Populating Next Right Pointers in Each Node
Given a binary tree struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right; TreeLinkNode *next; }Populate each next pointer to point to its next right node.
2015-03-29 18:06:48
407
原创 Json转换利器Gson——简单对象转化和带泛型的List转化
Gson 是 Google 提供的用来在 Java 对象和 JSON 数据之间进行映射的 Java 类库。可以将一个 JSON 字符串转成一个 Java 对象，或者反过来。先下载对应jar包：gson-1.6.jar实体类:[java] view plaincopypublic class Student { priva
2015-03-27 12:27:27
765
原创 LeetCode:Combinations
Given two integers n and k, return all possible combinations of k numbers out of 1 ... n.For example,If n = 4 and k = 2, a solution is:[ [2,4], [3,4], [2,3], [1,2], [1,3], [1,4],]
2015-03-26 21:49:54
444
原创 通过Servlet创建服务器端JSON数据
服务端提供JSON数据接口：http://localhost:8080/JSONInterface/servlet/jsservlet首先要导入项目所需要的jar包。package com.shuai.JsonManager;import java.io.IOException;import java.io.PrintWriter;import java.util.HashMap;
2015-03-26 15:34:57
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原创 LeetCode:Jump Game
Given an array of non-negative integers, you are initially positioned at the first index of the array.Each element in the array represents your maximum jump length at that position.Determine i
2015-03-25 20:34:21
484
原创 二叉树的深度优先和广度优先遍历
深度优先搜索算法（Depth First Search），是搜索算法的一种。是沿着树的深度遍历树的节点，尽可能深的搜索树的分支。当节点v的所有边都己被探寻过，搜索将回溯到发现节点v的那条边的起始节点。这一过程一直进行到已发现从源节点可达的所有节点为止。如果还存在未被发现的节点，则选择其中一个作为源节点并重复以上过程，整个进程反复进行直到所有节点都被访问为止。二叉树的深度优先遍历和先序遍
2015-03-20 10:18:02
819
原创 Leetcode:Excel Sheet Column Title
Given a positive integer, return its corresponding column title as appear in an Excel sheet.For example: 1 -> A 2 -> B 3 -> C ... 26 -> Z 27 -> AA 28 -> AB 思路：Beca
2015-02-18 16:34:44
664
原创 Leetcode:Largest Number
Given a list of non negative integers, arrange them such that they form the largest number.For example, given [3, 30, 34, 5, 9], the largest formed number is 9534330.Note: The result may be ve
2015-02-17 12:49:53
677
原创 Leetcode:Gray Code
The gray code is a binary numeral system where two successive values differ in only one bit.Given a non-negative integer n representing the total number of bits in the code, print the sequence of
2015-02-13 01:38:47
540
原创 Leetcode:Insertion Sort List
Sort a linked list using insertion sort.插入排序：每步将一个待排序的纪录，按其关键码值的大小插入前面已经排序的文件中适当位置上，直到全部插入完为止。实现代码：class Solution{public: ListNode *insertionSortList(ListNode *head) { if(head=
2015-02-11 20:43:10
587
原创 Leetcode：Binary Tree Preorder Traversal
Given a binary tree, return the preorder traversal of its nodes' values.For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3return [1,2,3].Note: Recursive soluti
2015-02-11 00:14:02
599
原创 Leetcode:Unique Binary Search Trees
Given n, how many structurally unique BST's (binary search trees) that store values 1...n?For example,Given n = 3, there are a total of 5 unique BST's. 1 3 3 2 1 \
2015-02-10 00:35:50
871
原创 Leetcode：Partition List
Given a linked list and a value x, partition it such that all nodes less than x come before nodes greater than or equal to x.You should preserve the original relative order of the nodes in each of
2015-02-07 14:13:58
572
原创 Leetcode:Add Two Numbers
You are given two linked lists representing two non-negative numbers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a link
2015-02-07 01:01:58
579
原创 Leetcode:Gas Station
There are N gas stations along a circular route, where the amount of gas at station i is gas[i].You have a car with an unlimited gas tank and it costs cost[i] of gas to travel from station i to
2015-02-05 15:20:17
525
原创 Leetcode:Majority Element
Given an array of size n, find the majority element. The majority element is the element that appears more than ⌊ n/2 ⌋ times.You may assume that the array is non-empty and the majority element
2015-02-04 22:20:59
410
转载 JAVA-组合与继承
设计原则：多用组合，少用继承。 组合和继承，都能实现对类的扩展。区别如下表所示：组合继承has-a关系is-a关系运行期决定编译期决定不破坏封装，整体和局部松耦合破坏封装，子类依赖父类支持扩展，随意增加组合类只能继承一个父类，必须包含所有方法，
2014-12-29 13:12:08
720
原创 Leetcode:Multiply Strings
Given two numbers represented as strings, return multiplication of the numbers as a string.Note: The numbers can be arbitrarily large and are non-negative. 实现两个字符串数字的乘法，模拟数学乘法即可。实现代码：
2014-12-17 15:50:25
479
原创 Leetcode:Single Number II
Given an array of integers, every element appears three times except for one. Find that single one.Note:Your algorithm should have a linear runtime complexity. Could you implement it without usi
2014-12-15 21:25:24
588
原创 Java操作MySQL数据库实现增删查改操作
要用到的jar包：mysql-connector-java-5.1.16-bin.jar，自行到网上下载即可。 根据实际配置数据库的信息： private String dbDriver = "com.mysql.jdbc.Driver"; private String dbUrl = "jdbc:mysql://[ip地址]:[端口号]/[数据库名]";//数据库的信息，根据
2014-12-15 15:16:21
1128
原创 Leetcode:Word Break
Word Break:Given a string s and a dictionary of words dict, determine if s can be segmented into a space-separated sequence of one or more dictionary words.For example, givens = "leetcode"
2014-12-12 19:47:37
548
原创 Leetcode：Valid Sudoku
Valid Sudoku：Determine if a Sudoku is valid, according to: Sudoku Puzzles - The Rules.点击打开链接The Sudoku board could be partially filled, where empty cells are filled with the character '.'.
2014-12-09 18:01:19
459
原创 Leetcode:3Sum Closest
3Sum Closest： Given an array S of n integers, find three integers in S such that the sum is closest to a given number, target. Return the sum of the three integers. You may assume that eac
2014-12-07 23:00:30
618
原创 Leetcode:Word Search
Word Search:Given a 2D board and a word, find if the word exists in the grid.The word can be constructed from letters of sequentially adjacent cell, where "adjacent" cells are those horizo
2014-12-05 16:26:14
637
原创 Leetcode:Path Sum与Path Sum II
Path Sum：Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.For example:Given the below binar
2014-12-01 14:20:03
472
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