stringbuilder | 易学教程

Hibernate: OutOfMemoryError persisting Blob when printing log message

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问题 I have a Hibernate Entity: @Entity class Foo { //... @Lob public byte[] getBytes() { return bytes; } //.... } My VM is configured with a maximum heap size of 512 MB. When I try to persist an object which has a 75 MB large object, I get an OutOfMemoryError. The names of the methods in the stack trace (StringBuilder, ByteArrayBlobType.toLoggableString, pretty.Printer.toString) suggest that hibernate is trying to write a very large log message that contains my object. Am I correct about why

Accessing the same string(StringBuilder) using multi-thread

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问题 My problem is if I use multi-thread on the same string sometime the string won't get replace.(I wrote this on notepad so syntax may be wrong) using System.Thread ... Others ofcourse class .... { private static StringBuild container = new StringBuilder(); static void Main(...) { container.Append(Read From File(Kind of long)); Thread thread1 = new Thread(Function1); Thread thread2 = new Thread(Function2); thread1.Start(); thread2.Start(); //Print out container } static void Function1 { //Do

Issue with java String and String Builder

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问题 I'm working on a project in which I have to decrypt a xml text from PHP server and parse into java, I have decrypted the xml text by using CipherInputStream and seen xml file fully get printed, but I'm facing a weird issue while trying to store the xml text in a java string, I'm working on the code below: public String decrypt(InputStream Fis){ Cipher c = Cipher.getInstance(algo + "/CBC/NoPadding"); String add = ""; StringBuilder getAns = new StringBuilder(); c.init(Cipher.DECRYPT_MODE, key);

Is that StringBuilder variable thread safe in this code?

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问题 Consider the below struts Action class in which, I am using a StringBuilder variable inside the execute method. My question: Is the variable sb threadsafe or not? public DemoAction extends Action { ...... public ActionForward execute(.....) { StringBuilder sb = new StringBuilder(); } } What if the same variable sb declared outside the execute(). Remember there will be only one object for DemoAction in WebContainer.? 回答1: Local variables are thread safe, as long as no other thread somehow gets

Is it true that StringBuilder is slower than concatenate a dozen of strings?

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问题 Is it true that StringBuilder is slower than concatenate a dozen of strings? How does compiler optimize the string concatenation so that joining a dozen of strings using "+" will be better than StringBuilder? From a book (written by Ben Watson) it says that: String Concatenation: For simple concatenation of a known (at compile time) quantity of strings, just use the ‘+’ operator or the String.Concat method. This is usually more efficient than using a StringBuilder. string result = a + b + c +

JavaSE-常用API

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目录目录第一章：API概述第二章：Scanner类第三章：Random类第四章：ArrayList类第五章：String类第六章：Arrays类第七章：Math类第八章：Object类第九章：Date类第十章：System类第十一章：StringBuilder类第十二章：包装类目录第一章：API概述什么是API？ API(Application Programming Interface)，应用程序编程接口。Java API是一本程序员的字典，是JDK中提供给我们使用的类的说明文档。这些类将底层的代码实现封装了起来，我们不需要关心这些类是如何实现的，只需要学习这些类如何使用即可。所以我们可以通过查询API的方式，来学习Java提供的类，并得知如何使用它们。 API使用步骤打开帮助文档。点击显示，找到索引，看到输入框。你要找谁？在输入框里输入，然后回车。看包。java.lang下的类不需要导包，其他需要。看类的解释和说明。学习构造方法。使用成员方法第二章：Scanner类 Scanner类介绍一个可以解析基本类型和字符串的简单文本扫描器使用步骤导包： import java.util.Scanner; 构造函数： public Scanner(InputStream source) 常用方法： public

c#操作串口类

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先放上串口的一个类，自己编写的，觉得这样好用些。 using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.IO.Ports; using System.Collections; using System.IO; using System.Text.RegularExpressions; namespace channel_ratio { public partial class Serial { private SerialPort comm = new SerialPort(); public StringBuilder builder = new StringBuilder();//避免在事件处理方法中反复的创建，定义到外面。接收到的数据 private long receive_count = 0;//接收计数 private long send_count = 0;//发送计数 private bool saveflag = false;/

Is it a Good Practice to Write HTML Using a StringBuilder in my ASP.NET Codebehind?

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问题 I'm interested to hear from other developers their opinion on an approach that I typically take. I have a web application, asp.net 2.0, c#. What I usually do to write out drop downs, tables, input controls, etc. is in the code behind use StringBuilder and write out something like sb.Append(" I don't find myself using to many .net controls as I typically write out the html in the code behind. When I want to use jQuery or call JavaScript I just put that function call in my sb.Append tag like sb

Is it possible to concatenate a list of strings using only a single allocation?

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问题 After doing some profiling, we've discovered that the current way in which our app concatenates strings causes an enormous amount of memory churn and CPU time. We're building a List<string> of strings to concatenate that is on the order of 500 thousand elements long, referencing several hundred megabytes worth of strings. We're trying to optimize this one small part of our app since it seems to account for a disproportionate amount of CPU and memory usage. We do a lot of text processing :)

跨服务器登录验证单点登录SSO 的过程和Java实现

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如果我们的网站需要和另一个域名做统一认证，也就是在我们网站登录，但真正的功能却在另一个网站来提供。许多都以 passport 的方式。整个认证可以分三步完成第一步：本地验证这个很简单，输入本地的用户名和密码，然后服务器认证通过，并返回正确的Cookie; 第二步：做远程认证，并返回远程连接通过本地Cookie,确认用户合法性，然后服务器端调用远程的登录程序，返回一个远程认证号的URL,这个URL里面包含了一个唯一的认证码，使用Location的方式第三步：远程登录客户端使用前一步的URL,访问远程的服务器，服务器确认认证码的正确性，再返回正确的远程Cookie. 至此，本地认证，通过一个URL,实现了远程认证。以下是师范代码，是Verycd的武林英雄的认证过程，其登录服务是verycd提供的，而真实服务时9wee提供的。 package org.javaren.hero;import java.io.BufferedReader;import java.io.InputStream;import java.io.InputStreamReader;import java.io.OutputStream;import java.net.Socket;import java.net.URLEncoder;import java.util.Scanner;/** *

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