java gs1-128

java gs1 128

java gs1 128

java barcode ean 128

java barcode ean 128

java gs1-128,
java ean 128,

java ean 128,

java gs1-128,
java barcode ean 128,
java ean 128,
java ean 128,
java gs1 128,
java gs1-128,
java ean 128,
java gs1 128,
java barcode ean 128,
java gs1-128,
java ean 128,
java gs1-128,
java ean 128,
java gs1-128,
java ean 128,
java ean 128,
java barcode ean 128,
java ean 128,

java gs1 128,
java ean 128,
java gs1-128,
java barcode ean 128,
java barcode ean 128,
java gs1-128,
java ean 128,
java barcode ean 128,
java gs1 128,
java gs1 128,
java gs1 128,
java barcode ean 128,
java gs1-128,
java ean 128,
java gs1 128,
java gs1-128,
java gs1 128,
java gs1 128,
java ean 128,
java gs1-128,
java gs1 128,
java gs1 128,
java ean 128,
java ean 128,
java ean 128,
java gs1 128,
java ean 128,
java ean 128,
java barcode ean 128,
java ean 128,
java gs1 128,
java gs1 128,
java gs1-128,
java barcode ean 128,
java gs1-128,
java gs1-128,
java barcode ean 128,
java gs1-128,
java barcode ean 128,
java gs1-128,
java gs1-128,
java gs1 128,
java gs1 128,
java ean 128,
java gs1 128,
java gs1-128,
java gs1 128,
java barcode ean 128,

You can now specify a system property, such as with java -displaysql=true, on the command line when you start your application, and this will automatically be applied to the Hibernate configuration property. The database connection pool settings deserve extra attention. The database connection pool Generally, it isn t advisable to create a connection each time you want to interact with the database. Instead, Java applications should use a pool of connections. Each application thread that needs to do work on the database requests a connection from the pool and then returns it to the pool when all SQL operations have been executed. The pool maintains the connections and minimizes the cost of opening and closing connections. There are three reasons for using a pool:

Acquiring a new connection is expensive. Some database management systems even start a completely new server process for each connection. Maintaining many idle connections is expensive for a database management system, and the pool can optimize the usage of idle connections (or disconnect if there are no requests). Creating prepared statements is also expensive for some drivers, and the connection pool can cache statements for a connection across requests.

Coding a custom filter reader Listing 20.7 shows our relatively straightforward EscapeFilter implementation.

Figure 2.2 shows the role of a connection pool in an unmanaged application runtime environment (that is, one without any application server).

package org.example.antbook; import org.apache.tools.ant.filters.BaseFilterReader; import org.apache.tools.ant.filters.ChainableReader; import java.io.Reader; import java.io.IOException; public class EscapeFilter extends BaseFilterReader implements ChainableReader { private String queuedData = null; public EscapeFilter(final Reader in) { super(in); } public Reader chain(Reader rdr) { EscapeFilter newFilter = new EscapeFilter(rdr); newFilter.setProject(getProject()); return newFilter; }

persistent instances. A cache concurrency strategy defines the transaction isolation details for a particular item of data, whereas the cache provider represents the physical cache implementation. Use of the second-level cache is optional and can be configured on a per-class and per-collection basis each such cache utilizes its own physical cache region.

public int read() throws IOException { if (queuedData != null && queuedData.length() == 0) { queuedData = null; } int ch = -1; if (queuedData != null) { ch = queuedData.charAt(0); Pulls one queuedData = queuedData.substring(1); character at if (queuedData.length() == 0) { a time from queuedData = null; the queue } } else { ch = in.read(); if (ch == -1) { return ch; End of data } queuedData = getEscapeString(ch); if (queuedData != null) { return read(); Starts reading from the queue } } return ch; } private String getEscapeString(int ch) { String output = null;

Hibernate also implements a cache for query resultsets that integrates closely with the second-level cache. This is an optional feature; it requires two additional physical cache regions that hold the cached query results and the timestamps when a table was last updated. We discuss the query cache in the next chapters because its usage is closely tied to the query being executed.

switch (ch) { case '<' : output = "<"; break; case '>' : output = ">"; break; case '"' : output = """; break; case '\'' : output = "'"; break; } if (output != null) { return output; } if (ch < 32 || ch > 127) { return "&#x" + Integer.toHexString(ch) + ";"; } return null; } }

We ve already discussed the first-level cache, the persistence context, in detail. Let s go straight to the optional second-level cache The Hibernate second-level cache The Hibernate second-level cache has process or cluster scope: All persistence contexts that have been started from a particular SessionFactory (or are associ-

ated with EntityManagers of a particular persistence unit) share the same second-level cache. Persistent instances are stored in the second-level cache in a disassembled form. Think of disassembly as a process a bit like serialization (the algorithm is much, much faster than Java serialization, however). The internal implementation of this process/cluster scope cache isn t of much interest. More important is the correct usage of the cache policies caching strategies and physical cache providers. Different kinds of data require different cache policies: The ratio of reads to writes varies, the size of the database tables varies, and some tables are shared with other external applications. The second-level cache is configurable at the granularity of an individual class or collection role. This lets you, for example, enable the second-level cache for reference data classes and disable it for classes that represent financial records. The cache policy involves setting the following: