http断点续传简单实现（java)

/* .s7o$u~l  
**SiteFileFetch.java f`/JY!uj{  
*/ a(d'iAU8^  
package NetFox; ~u,g5  
import java.io.*; xx!o]D-}  
import java.net.*; 1ww|km  
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public class SiteFileFetch extends Thread { #3kR}Amow  
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SiteInfoBean siteInfoBean = null; //文件信息Bean >@h0@N  
long[] nStartPos; //开始位置 jpm}EOq<%  
long[] nEndPos; //结束位置 EJdq"6S  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 2$qeNy  
long nFileLength; //文件长度 *v l_3S5_  
boolean bFirst = true; //是否第一次取文件 _f^q!tP&d  
boolean bStop = false; //停止标志 *=^
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File tmpFile; //文件下载的临时信息 uW Q`  
DataOutputStream output; //输出到文件的输出流 s:I^AL5  
&[R&@l Y  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） ,dZ 9=]  
public SiteFileFetch(SiteInfoBean bean) throws IOException '~liDz*O   
{ 1hi^  
siteInfoBean = bean; d@,q6R}!MP  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); i
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tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); J +<|8D  
if(tmpFile.exists ()) 8ru@ 8|r  
{ ]y-r
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bFirst = false; cX*  
read_nPos(); !Q#u i[0q  
} u+8_et5T  
else ~g1@-)zYxK  
{ 2kCJqyWy
 
nStartPos = new long[bean.getNSplitter()]; D!qtb6<.  
nEndPos = new long[bean.getNSplitter()]; 4.H!rkMM  
} Vk0O^o  
 kQX,MP(  
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} iW)FjDTP  
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public void run() H+*o @0C\~  
{ Zu~ #d)l3N  
//获得文件长度 FA4bv9:hi  
//分割文件 "%>/rh2Iq  
//实例FileSplitterFetch WdIr3  
//启动FileSplitterFetch线程 +yCIA\i#t6  
//等待子线程返回 gI\J sN  
try{ E\RQm}Z09  
if(bFirst) M%9PVePOe  
{ C7qbofoV  
nFileLength = getFileSize(); zFQxW4G  
if(nFileLength == -1) if^\Gs$  
{ =;@5Ue J  
System.err.println("File Length is not known!"); EZBk;*=B  
} V3I&0P k  
else if(nFileLength == -2) B8w0DJ  
{
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System.err.println("File is not access!"); T(3"bS.,  
} 3(FJ<,"D}  
else ]^aece t  
{ ;Iv)J|*  
for(int i=0;i<nStartPos.length;i++) S=M$g#X`5  
{ Ce`{M&NSWX  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); t3U*rr|A  
} :LcR<>LZ  
for(int i=0;i<nEndPos.length-1;i++) w_\niqm<y  
{ ze,HNFg@>  
nEndPos = nStartPos[i+1]; ^5"s3Qn  
} t;y>q  
nEndPos[nEndPos.length-1] = nFileLength; H;IG\k6C  
} p^~l
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} KY4|C05,  
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//启动子线程 ?~u"w OH'  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; :K2N7?shA  
for(int i=0;i<nStartPos.length;i++) r7w&
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{ hQl3F6-ud  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), pB
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siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), l'-iIbKX  
nStartPos,nEndPos,i); Pi)`[\{  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); \JN<"/  
fileSplitterFetch.start(); yfuvU2nVH  
} "C}nS=]8m  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), [/5>)HK} C  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); [ &R-YQ@  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", WWq)CwR  
nEndPos = " + nFileLength); &o:ZOD.  
// fileSplitterFetch[nPos.length-1].start(); yUEUIPL  
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//等待子线程结束 |h6)p;`gc  
//int count = 0; G^ n|9)CVW  
//是否结束while循环 L>pP3[~DV  
boolean breakWhile = false; i,* DWD+  
1N:eM/a  
!BK^5,4?--  
while(!bStop) )"j_NlO  
{ 0jj }jw  
write_nPos(); Vs9fAAXS4  
Utility.sleep(500); gEPCXf  
breakWhile = true; SznNvd <  
8
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for(int i=0;i<nStartPos.length;i++) CIYD'zR[2  
{ _Se>X=  
if(!fileSplitterFetch.bDownOver) >I!dJH/gj  
{ {N7,=(-2=  
breakWhile = false; KOwEw~  
break; 9)H~I/9Y  
} tJ'U<s  
} ]lm9D@HMC  
if(breakWhile) ]+fL6"OD/2  
break; >Q"eaJxE!l  
?t?!)#X  
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//count++; P]!eM(  
//if(count>4) :5C9uW#  
// siteStop(); (QqKttL:  
} ZTHrjW1  
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System.err.println("文件下载结束！"); cAIS?]1  
} FDpNM\SR1l  
catch(Exception e){e.printStackTrace ();} ^\Jg {9a  
} |A0kbC.  
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}  
//获得文件长度 bha_bj  
public long getFileSize() \s+<
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{ x!LUhX '  
int nFileLength = -1; m!!uf/  
try{ H|75,!<  
URL url = new URL(siteInfoBean.getSSiteURL()); &eg]8kV  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); [Zgy,j\\  
httpConnection.setRequestProperty("User-Agent","NetFox"); =C5[75z#+  
$+V{2k4X,  
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int responseCode=httpConnection.getResponseCode(); zBqr15  
if(responseCode>=400) #YjV3O5<  
{ !"p,9  
processErrorCode(responseCode); vhKeW(z  
return -2; //-2 represent access is error &/Tx@j^.C  
} <>
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String sHeader; hLJO\=0rJz  
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for(int i=1;;i++) 0^{zq|%Q!  
{ ,]20I _  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); OJ]{FI  
//Utility.log(in.readLine()); >8jDW "Ua  
sHeader=httpConnection.getHeaderFieldKey(i); ?Cmb3pX^\  
if(sHeader!=null) 'VR5>r  
{ BOfO$J}  
if(sHeader.equals("Content-Length")) b]CJf8'u  
{ 0D0#*J  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 9Q].cDe[  
break; yvNYY
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} ,CwhpW\Y  
} H+_oK ]/  
else /rJvw  
break; s9O] tk  
} SLZv`  
} t_P1a0Zu  
catch(IOException e){e.printStackTrace ();} r_ r+&4n  
catch(Exception e){e.printStackTrace ();} OM2|c}]ZQ  

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Utility.log(nFileLength); ,gD30Pylz  
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return nFileLength; hFQC%N.'  
} ki}Uw#  
8>O'_6Joj  
?55('+{l  
//保存下载信息（文件指针位置） cDE?Xo'!  
private void write_nPos() TSE(K
t  
{ QF-.")Z  
try{ `1pri
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output = new DataOutputStream(new FileOutputStream(tmpFile)); .8.ivfmJh  
output.writeInt(nStartPos.length); REFisH-  
for(int i=0;i<nStartPos.length;i++) X2sK<Qluql  
{ RAf+%h*  
// output.writeLong(nPos); zXVQLz5  
output.writeLong(fileSplitterFetch.nStartPos); q@Q|oB0W$)  
output.writeLong(fileSplitterFetch.nEndPos); I+u=H2][2  
} x40R)Led  
output.close(); US> m1KsX  
} iAup',AZg  
catch(IOException e){e.printStackTrace ();} uiHlaMf  
catch(Exception e){e.printStackTrace ();} |a^ydwb  
} |Zkcs]8M!  
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//读取保存的下载信息（文件指针位置） }yB@?  
private void read_nPos() mc9$"  
{ 3PBg3Y$  
try{ j|+B|  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); H
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int nCount = input.readInt(); 9(u2j
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nStartPos = new long[nCount]; 73N%_8DH  
nEndPos = new long[nCount]; xx/DD%IZ  
for(int i=0;i<nStartPos.length;i++) :i:Zc~%  
{ ?\^u},HnE|  
nStartPos = input.readLong(); :q6hT<f;  
nEndPos = input.readLong(); #9 }Oqm  
} Z\dILt:#z  
input.close(); X*FK6,Y|(  
} )OjbmU!7  
catch(IOException e){e.printStackTrace ();} i<=@7W  
catch(Exception e){e.printStackTrace ();} u45e>F=  
} 1l1
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2.; OHQTE  
})&0
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private void processErrorCode(int nErrorCode) I-;JDC?  
{ 94K;=5h  
System.err.println("Error Code : " + nErrorCode); QouTMS-b  
} ](8XC_-U'  

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//停止文件下载 tK8
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public void siteStop() "gK2!N|#  
{ Zz/w>kAG*{  
bStop = true; uP+ j_is
 
for(int i=0;i<nStartPos.length;i++) b[BSUdCB  
fileSplitterFetch.splitterStop(); yChC&kX Z+  
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} 9)f1CC]
 
} Ww8C![ ,  
//负责部分文件的抓取 ;#f%vs>Y7i  
**FileSplitterFetch.java 1f}S:Z  
*/ ,pAMQ5  
package NetFox; 9N'$Y*. d<  
lXB_HDY  
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import java.io.*; >6<g5ps.n  
import java.net.*; a"WnBdFZ  
c/g(=F__[  
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public class FileSplitterFetch extends Thread { E]ZM`bex&  
=8tduB  
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String sURL; //File URL f_z2d+  
long nStartPos; //File Snippet Start Position ?BWWb   
long nEndPos; //File Snippet End Position V8,$<1Fi;-  
int nThreadID; //Thread's ID {J99F  
boolean bDownOver = false; //Downing is over />f`X+d  
boolean bStop = false; //Stop identical xRaYm  
FileAccessI fileAccessI = null; //File Access interface ShSh/0   
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 5[Q44$a{  
{ XeZv%` ?  
this.sURL = sURL; EoOrA@N  
this.nStartPos = nStart; wvUph[j}J  
this.nEndPos = nEnd; [
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nThreadID = id; jj.yB#T  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 BJ&>'rc  
} Kvk;D ]$  
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public void run() tcRK\  
{ 6Qx
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while(nStartPos < nEndPos && !bStop) 3mBrnq]j>  
{ i\`[0dfY  
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try{ !\"C
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URL url = new URL(sURL); %K%8 ~B  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); D|+H!f{k  
httpConnection.setRequestProperty("User-Agent","NetFox"); 6.By)L  
String sProperty = "bytes="+nStartPos+"-"; }Y-f+qX*  
httpConnection.setRequestProperty("RANGE",sProperty); A\:=p  
Utility.log(sProperty); ^ qE4:|e  
'x!q*|zF2  
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InputStream input = httpConnection.getInputStream(); Q2Q`g`*O:  
//logResponseHead(httpConnection); 
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byte[] b = new byte[1024]; @B1rtw6  
int nRead; bJe^x;J9  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) %GHHnf%2Z  
{ v3hNvcMpf  
nStartPos += fileAccessI.write(b,0,nRead); +\}]`uS:  
//if(nThreadID == 1) ZegsV|  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); xeu] X|,  
} xorFz{  
!'PPj_Hp]  
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Utility.log("Thread " + nThreadID + " is over!"); r3iNfY b  
bDownOver = true; m&; t;&#  
//nPos = fileAccessI.write (b,0,nRead); IOfo]p-  
} H]}- U8}sp  
catch(Exception e){e.printStackTrace ();} E8?Q>%_  
} g\X"E>X  
} qk:F6kL\`  
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//打印回应的头信息 GR|Vwxs<@P  
public void logResponseHead(HttpURLConnection con) ~_h4
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{ Y6g[y\*t  
for(int i=1;;i++) A$^}zP'u0<  
{ W_kJb  
String header=con.getHeaderFieldKey(i); q>H!?zi\Hy  
if(header!=null) 44S<(Re  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); ;9;.!4g/T  
Utility.log(header+" : "+con.getHeaderField(header)); I.\u2B/?  
else k*^.-v  
break; czedn_}%Q  
} nY(jN D  
} N*@bJ*0  
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*D`,z3/*  
public void splitterStop() Z1q'4h=F.  
{ m6g+ B>  
bStop = true; 8zZR%fZ  
} PhW#=S  
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} Lmj?V1% V  
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/* a1om8!C  
**FileAccess.java (4b&}46  
*//文件访问(定位，写) M@csB.'  
package NetFox; S _#UEf  
import java.io.*; '3|OgV  
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public class FileAccessI implements Serializable{ pk"JcUzR  
9X=#wh,q  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 V ;>{-p  
RandomAccessFile oSavedFile; 12cfqIo9  
long nPos; %yptML9  
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public FileAccessI() throws IOException J'2R-CI,  
{ m,=$a\UC  
this("",0); BPi>SI0  
} nw\p3  
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public FileAccessI(String sName,long nPos) throws IOException Qaagi `  
{ @#o$~'my  
oSavedFile = new RandomAccessFile(sName,"rw"); j*+r`CX  
this.nPos = nPos; *~fN^{B'!  
oSavedFile.seek(nPos); yv'mV=BMJ!  
} v[lytX4)  
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public synchronized int write(byte[] b,int nStart,int nLen) R]ppA=1*_l  
{ !3T x\a`?/  
int n = -1; %/'[GC'y!  
try{ +mxsjcq0  
oSavedFile.write(b,nStart,nLen); MT
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n = nLen; YQ?|Vb U  
} .+B!mmp  
catch(IOException e) J-X5n 3I&  
{ O4-UVxv}  
e.printStackTrace (); -"a])- j  
} wmoOp;C  
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return n; blp)a  
} ` D4J9;|;]  
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} I5 2wTl0  
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/* o}Xp-P   
**SiteInfoBean.java j*6!7u.,K  
*/ r&TxRsg{  
package NetFox; O050Q5zy  
AJmS1 B  
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public class SiteInfoBean { ,*C^ixNE  
4&&j7$aV  
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private String sSiteURL; //Site's URL +ckj]yA;  
private String sFilePath; //Saved File's Path tv;3~Y0i  
private String sFileName; //Saved File's Name 134wK]d^  
private int nSplitter; //Count of Splited Downloading File i!Ne<Q  
.{8lG^0U<  
WcUeWGC>  
public SiteInfoBean() %/>_o{"hw  
{//nSplitter的缺省值为5 tPp}/a%D  
//default value of nSplitter is 5 L\"=H4r  
this("","","",5); *tP,Ol  
} HX <;=m  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) {+`ep\.$&  
{ (d!vm\-PH  
sSiteURL= sURL; Sa<R8X'J  
sFilePath = sPath; dm.3.xXq  
sFileName = sName; gr
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this.nSplitter = nSpiltter; 8[y7(Xw  
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} oiR`\uY  
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public String getSSiteURL() Gge"`AT  
{ _p~ `nQ=7  
return sSiteURL; , D&FCs%v  
} <LLSUk/  
}k,Si9O  
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public void setSSiteURL(String value) @D7cv"   
{ DSIa3!0  
sSiteURL = value;   ()SG  
} x,1&ml5  
oF3#]6`;/  
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public String getSFilePath() |Rab'9U^  
{
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return sFilePath; \K)q$E<!  
} MZ+"Arzb  
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public void setSFilePath(String value) ; aMMIp  
{ ]#J]f  
sFilePath = value; 2Hq!YsJ4]  
} UkGUxQ,GU  
XCt}>/"s\h  
_PRm4 :  
public String getSFileName() V&f3>#n\  
{ EoY570PN  
return sFileName; JY_' d,O  
} 4e5Ka{# <  
"OWq]q#  
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public void setSFileName(String value) ",K6zALJ  
{ *D9QwQ _|  
sFileName = value; H-S28%.  
} vUCU%>F  
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public int getNSplitter() _-h3>.;h9  
{ DG& kY+  
return nSplitter; %f>V\z_C  
} :o
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public void setNSplitter(int nCount) f:=?"MX7  
{ 19lx;^b  
nSplitter = nCount; %]:u^\7  
} q,m6$\g4  
} Nlo*vu  
2R)Y}*VX  
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/* ++FMkeHZ  
**Utility.java ~xA'-N/  
*/ _El=M0  
package NetFox; _p90Zm-3X  
V%3K")  
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public class Utility { gTs5xDvJ  
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public Utility() ]ErAa"?  
{ ;BpuNB  
dhV=;'   
#LcF;1o%o2  
} \N!k)6\  
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//线程睡眠 SB]|y-su  
public static void sleep(int nSecond) IV!&jL  
{ 2pZ|+!xc+  
try{ 5B"j\TwQ  
Thread.sleep(nSecond); ;K`qSX;;c(  
} O.!|;)HQ  
catch(Exception e) ``0knr <  
{ T?Hs_u{  
e.printStackTrace (); 02bv0  
} 6 Rg{^ERf  
} &i6WVNGy  
D4[t@*m>7  
//日志 }oloMtp$  
public static void log(String sMsg) bW[Y:}Hk~  
{ # bP1rQ0
 
System.err.println(sMsg); h_fA  
} Pij*?qmeQ  
TLw.rEN!;  
0~)cAKus  
public static void log(int sMsg) B`9'COw  
{ He~)i)co  
System.err.println(sMsg); ub7|'+5  
} abx/h#_q  
} <`n T+c  
]qvrpI!E!  
6-j><'  
/* 6f{Kj)  
**TestMethod.java SfEgmp-m  
*/ gT?
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package NetFox; |*K AqTO0  
%?@N-$j  
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public class TestMethod { `ZC_F! E  
hCuUX)>Bt  
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public TestMethod() fH}#.vy  
{ ///xx/weblogic60b2_win.exe r[ni{&  
try{ criOJ-  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 1-.6psE  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); aHuZzYQ*"j  
SiteFileFetch fileFetch = new SiteFileFetch(bean); ViKN|W>T  
fileFetch.start(); $oD
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} GHaD32  
catch(Exception e){e.printStackTrace ();} WzDL(~m+Z  
 At3>  
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} J!YB_6b  
=ss(~[  
.!/w[Z]  
public static void main(String[] args) aQzx^%B1  
{ waT'|9{  
new TestMethod(); rom`%qp^  
} Gl;xd  
} ObnQ,x(  
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