Sách ebook Java

Contents

Foreword . xvii

Preface .xxi

Chapter 1: Overview . 1

Distributed Multitiered Applications 2
J2EE Components 3
J2EE Clients 4
Web Components 6
Business Components 6
Enterprise Information System Tier 8
J2EE Containers 8
Container Services 8
Container Types 9
Packaging 10
Development Roles 11
J2EE Product Provider 12
Tool Provider 12
Application Component Provider 12
Application Assembler 13
Application Deployer and Administrator 14
Reference Implementation Software 14
Database Access 15
J2EE APIs 15
Simplified Systems Integration 18
Tools 19

vi CONTENTS

Chapter 2: Getting Started .21

Setting Up 22
Getting the Example Code 22
Getting the Build Tool (ant) 22
Checking the Environment Variables 23
Starting the J2EE Server 23
Starting the deploytool 23
Creating the J2EE Application 24
Creating the Enterprise Bean 24
Coding the Enterprise Bean 24
Compiling the Source Files 26
Packaging the Enterprise Bean 26
Creating the J2EE Application Client 28
Coding the J2EE Application Client 28
Compiling the Application Client 31
Packaging the J2EE Application Client 31
Specifying the Application Client’s Enterprise Bean Reference 32
Creating the Web Client 32
Coding the Web Client 32
Compiling the Web Client 34
Packaging the Web Client 34
Specifying the Web Client’s Enterprise Bean Reference 35
Specifying the JNDI Names 35
Deploying the J2EE Application 37
Running the J2EE Application Client 37
Running the Web Client 38
Modifying the J2EE Application 39
Modifying a Class File 39
Adding a File 39
Modifying the Web Client 39
Modifying a Deployment Setting 40
Common Problems and Their Solutions 40
Cannot Start the J2EE Server 40
Compilation Errors 41
Deployment Errors 42
J2EE Application Client Runtime Errors 43
Web Client Runtime Errors 44
Detecting Problems With the Verifier Tool 45
Comparing Your EAR Files with Ours 45
When All Else Fails 45

v
CONTENTS vii

Chapter 3: Enterprise Beans 47

What Is an Enterprise Bean? 48
Benefits of Enterprise Beans 48
When to Use Enterprise Beans 49
Types of Enterprise Beans 49
What Is a Session Bean? 49
State Management Modes 50
When to Use Session Beans 51
What Is an Entity Bean? 51
What Makes Entity Beans Different from Session Beans? 52
Container-Managed Persistence 53
When to Use Entity Beans 56
What Is a Message-Driven Bean? 56
What Makes Message-Driven Beans Different from Session
and Entity Beans? 57
When to Use Message-Driven Beans 57
Defining Client Access with Interfaces 58
Remote Access 58
Local Access 59
Local Interfaces and Container-Managed Relationships 59
Deciding on Remote or Local Access 60
Performance and Access 61
Method Parameters and Access 61
The Contents of an Enterprise Bean 62
Naming Conventions for Enterprise Beans 62
The Life Cycles of Enterprise Beans 63
The Life Cycle of a Stateful Session Bean 63
The Life Cycle of a Stateless Session Bean 64
The Life Cycle of an Entity Bean 65
The Life Cycle of a Message-Driven Bean 67

Chapter 4: A Session Bean Example . 69

The CartEJB Example 70
Session Bean Class 70
Home Interface 74
Remote Interface 76
Helper Classes 76
Running the CartEJB Example 76
Other Enterprise Bean Features 78
Accessing Environment Entries 78
Comparing Enterprise Beans 80
Passing an Enterprise Bean’s Object Reference 80